diff --git a/src/client/application/application-attachment-manager.vala b/src/client/application/application-attachment-manager.vala
index 805ecb6f..f4b5eb06 100644
--- a/src/client/application/application-attachment-manager.vala
+++ b/src/client/application/application-attachment-manager.vala
@@ -40,7 +40,7 @@ public class Application.AttachmentManager : GLib.Object {
                                        GLib.Cancellable? cancellable) {
         if (attachments.size == 1) {
             return yield save_attachment(
-                Geary.Collection.get_first(attachments), null, cancellable
+                Geary.Collection.first(attachments), null, cancellable
             );
         } else {
             return yield save_all(attachments, cancellable);
diff --git a/src/client/application/application-client.vala b/src/client/application/application-client.vala
index aa853fba..0e75cde9 100644
--- a/src/client/application/application-client.vala
+++ b/src/client/application/application-client.vala
@@ -808,7 +808,23 @@ public class Application.Client : Gtk.Application {
         this.controller.register_window(window);
         window.focus_in_event.connect(on_main_window_focus_in);
         if (select_first_inbox) {
-            window.select_first_inbox(true);
+            if (!window.select_first_inbox(true)) {
+                // The first inbox wasn't selected, so the account is
+                // likely still loading folders after being
+                // opened. Add a listener to try again later.
+                try {
+                    Geary.Account? first = Geary.Collection.first<Geary.Account>(
+                        this.engine.get_accounts()
+                    );
+                    if (first != null) {
+                        first.folders_available_unavailable.connect_after(
+                            on_folders_first_available
+                        );
+                    }
+                } catch (GLib.Error error) {
+                    debug("Error getting Inbox for first account");
+                }
+            }
         }
         return window;
     }
@@ -1005,13 +1021,9 @@ public class Application.Client : Gtk.Application {
         // If there was an existing active main, select the same
         // account/folder/conversation.
         MainWindow? current = this.last_active_main_window;
-        // Make a copy of the selection so the underlying collection
-        // doesn't change as the selection does.
         this.new_window.begin(
             current.selected_folder,
-            Geary.traverse(
-                current.conversation_list_view.get_selected_conversations()
-            ).to_linked_list()
+            current.conversation_list_view.copy_selected()
         );
     }
 
@@ -1093,6 +1105,18 @@ public class Application.Client : Gtk.Application {
         }
     }
 
+    private void on_folders_first_available(Geary.Account account,
+        Gee.BidirSortedSet<Geary.Folder>? available,
+        Gee.BidirSortedSet<Geary.Folder>? unavailable
+    ) {
+        if (get_active_main_window().select_first_inbox(true)) {
+            // The handler has done its job, so disconnect it
+            account.folders_available_unavailable.disconnect(
+                on_folders_first_available
+            );
+        }
+    }
+
     private bool on_main_window_focus_in(Gtk.Widget widget,
                                          Gdk.EventFocus event) {
         MainWindow? main = widget as MainWindow;
@@ -1107,7 +1131,7 @@ public class Application.Client : Gtk.Application {
         if (main != null) {
             this.controller.unregister_window(main);
             if (this.last_active_main_window == main) {
-                this.last_active_main_window = Geary.Collection.get_first(
+                this.last_active_main_window = Geary.Collection.first(
                     get_main_windows()
                 );
             }
diff --git a/src/client/application/application-controller.vala b/src/client/application/application-controller.vala
index 909cade5..ec46ed5d 100644
--- a/src/client/application/application-controller.vala
+++ b/src/client/application/application-controller.vala
@@ -227,27 +227,6 @@ internal class Application.Controller : Geary.BaseObject {
             warning("Error loading accounts: %s", e.message);
         }
 
-        // Since the accounts may still be loading folders, when the
-        // main window first opens no folder might be available to be
-        // selected. Add look for the inbox and if not found, add a
-        // listener here as a once off for when it is loaded.
-        if (!application.get_active_main_window().select_first_inbox(true)) {
-            // Connect after so the folder is added to any
-            // open main windows first.
-            try {
-                Geary.Account first = Geary.Collection.get_first(
-                    application.engine.get_accounts()
-                );
-                if (first != null) {
-                    first.folders_available_unavailable.connect_after(
-                        on_folders_first_available
-                    );
-                }
-            } catch (GLib.Error error) {
-                debug("Error getting Inbox for first account");
-            }
-        }
-
         // Expunge any deleted accounts in the background, so we're
         // not blocking the app continuing to open.
         this.expunge_accounts.begin();
@@ -1387,18 +1366,6 @@ internal class Application.Controller : Geary.BaseObject {
         }
     }
 
-    private void on_folders_first_available(Geary.Account account,
-        Gee.BidirSortedSet<Geary.Folder>? available,
-        Gee.BidirSortedSet<Geary.Folder>? unavailable
-    ) {
-        if (application.get_active_main_window().select_first_inbox(true)) {
-            // The handler has done its job, so disconnect it
-            account.folders_available_unavailable.disconnect(
-                on_folders_first_available
-            );
-        }
-    }
-
     private bool should_notify_new_messages(Geary.Folder folder) {
         // A monitored folder must be selected to squelch notifications;
         // if conversation list is at top of display, don't display
diff --git a/src/client/application/application-main-window.vala b/src/client/application/application-main-window.vala
index d9be7a5a..0012727c 100644
--- a/src/client/application/application-main-window.vala
+++ b/src/client/application/application-main-window.vala
@@ -586,7 +586,7 @@ public class Application.MainWindow :
             if (loaded.size == 1) {
                 // A single conversation was loaded, so ensure we
                 // scroll to the email in the conversation.
-                Geary.App.Conversation target = Geary.Collection.get_first(loaded);
+                Geary.App.Conversation? target = Geary.Collection.first(loaded);
                 ConversationListBox? current_list =
                     this.conversation_viewer.current_list;
                 if (current_list != null &&
@@ -860,7 +860,7 @@ public class Application.MainWindow :
     private Geary.Folder? get_first_inbox() {
         Geary.Folder? inbox = null;
         try {
-            Geary.Account first = Geary.Collection.get_first(
+            Geary.Account? first = Geary.Collection.first<Geary.Account>(
                 this.application.engine.get_accounts()
             );
             if (first != null) {
@@ -1285,7 +1285,7 @@ public class Application.MainWindow :
 
             case 1:
                 update_conversation_actions(SINGLE);
-                Geary.App.Conversation convo = Geary.Collection.get_first(to_select);
+                Geary.App.Conversation? convo = Geary.Collection.first(to_select);
 
                 // It's possible for a conversation with zero email to
                 // be selected, when it has just evaporated after its
@@ -1576,7 +1576,7 @@ public class Application.MainWindow :
                 Gee.Collection<Geary.EmailIdentifier> ids =
                     new Gee.LinkedList<Geary.EmailIdentifier>();
                 foreach (Geary.App.Conversation convo in
-                         this.conversation_list_view.get_selected_conversations()) {
+                         this.conversation_list_view.get_selected()) {
                     ids.add_all(convo.get_email_ids());
                 }
                 try {
@@ -1874,13 +1874,9 @@ public class Application.MainWindow :
     private void on_conversation_activated(Geary.App.Conversation activated) {
         if (this.selected_folder != null) {
             if (this.selected_folder.special_folder_type != DRAFTS) {
-                // Make a copy of the selection so the underlying
-                // collection doesn't change as the selection does.
                 this.application.new_window.begin(
                     this.selected_folder,
-                    Geary.traverse(
-                        this.conversation_list_view.get_selected_conversations()
-                    ).to_linked_list()
+                    this.conversation_list_view.copy_selected()
                 );
             } else {
                 // TODO: Determine how to map between conversations
@@ -1974,7 +1970,7 @@ public class Application.MainWindow :
         bool starred_selected = false;
         bool unstarred_selected = false;
         foreach (Geary.App.Conversation conversation in
-                 this.conversation_list_view.get_selected_conversations()) {
+                 this.conversation_list_view.get_selected()) {
             if (conversation.is_unread())
                 unread_selected = true;
 
@@ -2031,7 +2027,7 @@ public class Application.MainWindow :
         if (location != null) {
             this.application.controller.mark_conversations.begin(
                 location,
-                this.conversation_list_view.get_selected_conversations(),
+                this.conversation_list_view.copy_selected(),
                 Geary.EmailFlags.UNREAD,
                 false,
                 (obj, res) => {
@@ -2050,7 +2046,7 @@ public class Application.MainWindow :
         if (location != null) {
             this.application.controller.mark_conversations.begin(
                 location,
-                this.conversation_list_view.get_selected_conversations(),
+                this.conversation_list_view.copy_selected(),
                 Geary.EmailFlags.UNREAD,
                 true,
                 (obj, res) => {
@@ -2069,7 +2065,7 @@ public class Application.MainWindow :
         if (location != null) {
             this.application.controller.mark_conversations.begin(
                 location,
-                this.conversation_list_view.get_selected_conversations(),
+                this.conversation_list_view.copy_selected(),
                 Geary.EmailFlags.FLAGGED,
                 true,
                 (obj, res) => {
@@ -2088,7 +2084,7 @@ public class Application.MainWindow :
         if (location != null) {
             this.application.controller.mark_conversations.begin(
                 location,
-                this.conversation_list_view.get_selected_conversations(),
+                this.conversation_list_view.copy_selected(),
                 Geary.EmailFlags.FLAGGED,
                 false,
                 (obj, res) => {
@@ -2112,7 +2108,7 @@ public class Application.MainWindow :
             this.application.controller.move_conversations_special.begin(
                 source,
                 destination,
-                this.conversation_list_view.get_selected_conversations(),
+                this.conversation_list_view.copy_selected(),
                 (obj, res) => {
                     try {
                         this.application.controller.move_conversations_special.end(res);
@@ -2131,7 +2127,7 @@ public class Application.MainWindow :
             this.application.controller.move_conversations.begin(
                 source,
                 destination,
-                this.conversation_list_view.get_selected_conversations(),
+                this.conversation_list_view.copy_selected(),
                 (obj, res) => {
                     try {
                         this.application.controller.move_conversations.end(res);
@@ -2151,7 +2147,7 @@ public class Application.MainWindow :
             this.application.controller.copy_conversations.begin(
                 source,
                 destination,
-                this.conversation_list_view.get_selected_conversations(),
+                this.conversation_list_view.copy_selected(),
                 (obj, res) => {
                     try {
                         this.application.controller.copy_conversations.end(res);
@@ -2170,7 +2166,7 @@ public class Application.MainWindow :
             this.application.controller.move_conversations_special.begin(
                 source,
                 ARCHIVE,
-                this.conversation_list_view.get_selected_conversations(),
+                this.conversation_list_view.copy_selected(),
                 (obj, res) => {
                     try {
                         this.application.controller.move_conversations_special.end(res);
@@ -2188,7 +2184,7 @@ public class Application.MainWindow :
             this.application.controller.move_conversations_special.begin(
                 source,
                 Geary.SpecialFolderType.TRASH,
-                this.conversation_list_view.get_selected_conversations(),
+                this.conversation_list_view.copy_selected(),
                 (obj, res) => {
                     try {
                         this.application.controller.move_conversations_special.end(res);
@@ -2204,7 +2200,7 @@ public class Application.MainWindow :
         Geary.FolderSupport.Remove target =
             this.selected_folder as Geary.FolderSupport.Remove;
         Gee.Collection<Geary.App.Conversation> conversations =
-            this.conversation_list_view.get_selected_conversations();
+            this.conversation_list_view.copy_selected();
         if (target != null && this.prompt_delete_conversations(conversations.size)) {
             this.application.controller.delete_conversations.begin(
                 target,
diff --git a/src/client/composer/composer-widget.vala b/src/client/composer/composer-widget.vala
index d47af36c..9bbd6660 100644
--- a/src/client/composer/composer-widget.vala
+++ b/src/client/composer/composer-widget.vala
@@ -624,24 +624,26 @@ public class Composer.Widget : Gtk.EventBox, Geary.BaseInterface {
 
             // Assemble the headers.
             if (email.length > 0 && headers.contains("to"))
-                this.to = "%s,%s".printf(email, Geary.Collection.get_first(headers.get("to")));
+                this.to = "%s,%s".printf(
+                    email, Geary.Collection.first(headers.get("to"))
+                );
             else if (email.length > 0)
                 this.to = email;
             else if (headers.contains("to"))
-                this.to = Geary.Collection.get_first(headers.get("to"));
+                this.to = Geary.Collection.first(headers.get("to"));
 
             if (headers.contains("cc"))
-                this.cc = Geary.Collection.get_first(headers.get("cc"));
+                this.cc = Geary.Collection.first(headers.get("cc"));
 
             if (headers.contains("bcc"))
-                this.bcc = Geary.Collection.get_first(headers.get("bcc"));
+                this.bcc = Geary.Collection.first(headers.get("bcc"));
 
             if (headers.contains("subject"))
-                this.subject = Geary.Collection.get_first(headers.get("subject"));
+                this.subject = Geary.Collection.first(headers.get("subject"));
 
             if (headers.contains("body"))
                 this.body_html = Geary.HTML.preserve_whitespace(Geary.HTML.escape_markup(
-                    Geary.Collection.get_first(headers.get("body"))));
+                    Geary.Collection.first(headers.get("body"))));
 
             Gee.List<string> attachments = new Gee.LinkedList<string>();
             attachments.add_all(headers.get("attach"));
diff --git a/src/client/conversation-list/conversation-list-view.vala b/src/client/conversation-list/conversation-list-view.vala
index ab1c5e57..96acc4b8 100644
--- a/src/client/conversation-list/conversation-list-view.vala
+++ b/src/client/conversation-list/conversation-list-view.vala
@@ -131,11 +131,18 @@ public class ConversationListView : Gtk.TreeView, Geary.BaseInterface {
         selection.changed.connect(on_selection_changed);
     }
 
-    /** Returns a read-only collection of the current selection. */
-    public Gee.Set<Geary.App.Conversation> get_selected_conversations() {
+    /** Returns a read-only iteration of the current selection. */
+    public Gee.Set<Geary.App.Conversation> get_selected() {
         return this.selected.read_only_view;
     }
 
+    /** Returns a copy of the current selection. */
+    public Gee.Set<Geary.App.Conversation> copy_selected() {
+        var copy = new Gee.HashSet<Geary.App.Conversation>();
+        copy.add_all(this.selected);
+        return copy;
+    }
+
     public void inhibit_next_autoselect() {
         this.should_inhibit_autoselect = true;
     }
@@ -288,13 +295,11 @@ public class ConversationListView : Gtk.TreeView, Geary.BaseInterface {
             // Get the current conversation.  If it's selected, we'll apply the mark operation to
             // all selected conversations; otherwise, it just applies to this one.
             Geary.App.Conversation conversation = get_model().get_conversation_at_path(path);
-            Gee.Collection<Geary.App.Conversation> to_mark;
-            if (this.selected.contains(conversation))
-                // take a copy of currently selected for handling to
-                // the signal
-                to_mark = get_selected_conversations();
-            else
-                to_mark = Geary.Collection.single(conversation);
+            Gee.Collection<Geary.App.Conversation> to_mark = (
+                this.selected.contains(conversation)
+                ? copy_selected()
+                : Geary.Collection.single(conversation)
+            );
 
             if (read_clicked) {
                 mark_conversations(to_mark, Geary.EmailFlags.UNREAD);
@@ -487,8 +492,8 @@ public class ConversationListView : Gtk.TreeView, Geary.BaseInterface {
         }
 
         // only notify if different than what was previously reported
-        if (!Geary.Collection.are_sets_equal<Geary.App.Conversation>(
-                this.selected, new_selection)) {
+        if (this.selected.size != new_selection.size ||
+            !this.selected.contains_all(new_selection)) {
             this.selected = new_selection;
             conversations_selected(this.selected.read_only_view);
         }
@@ -515,18 +520,18 @@ public class ConversationListView : Gtk.TreeView, Geary.BaseInterface {
 
     // Always returns false, so it can be used as a one-time SourceFunc
     private bool update_visible_conversations() {
+        bool changed = false;
         Gee.Set<Geary.App.Conversation> visible_conversations = get_visible_conversations();
-        if (current_visible_conversations != null
-            && Geary.Collection.are_sets_equal<Geary.App.Conversation>(
-            current_visible_conversations, visible_conversations)) {
-            return false;
+        if (this.current_visible_conversations == null ||
+            this.current_visible_conversations.size != visible_conversations.size ||
+            !this.current_visible_conversations.contains_all(visible_conversations)) {
+            this.current_visible_conversations = visible_conversations;
+            visible_conversations_changed(
+                this.current_visible_conversations.read_only_view
+            );
+            changed = true;
         }
-
-        current_visible_conversations = visible_conversations;
-
-        visible_conversations_changed(current_visible_conversations.read_only_view);
-
-        return false;
+        return changed;
     }
 
     private void schedule_visible_conversations_changed() {
diff --git a/src/client/conversation-viewer/conversation-list-box.vala b/src/client/conversation-viewer/conversation-list-box.vala
index 377f66e6..4e501aa4 100644
--- a/src/client/conversation-viewer/conversation-list-box.vala
+++ b/src/client/conversation-viewer/conversation-list-box.vala
@@ -678,7 +678,7 @@ public class ConversationListBox : Gtk.ListBox, Geary.BaseInterface {
                 id => this.conversation.contains_email_by_id(id)
             ).to_array_list();
             valid_scroll_to.sort((a, b) => a.natural_sort_comparator(b));
-            var first_scroll = Geary.Collection.get_first(valid_scroll_to);
+            var first_scroll = Geary.Collection.first(valid_scroll_to);
 
             if (first_scroll != null) {
                 foreach (Geary.Email email in all_email) {
diff --git a/src/client/conversation-viewer/conversation-viewer.vala b/src/client/conversation-viewer/conversation-viewer.vala
index 2c3ec220..3d2a0226 100644
--- a/src/client/conversation-viewer/conversation-viewer.vala
+++ b/src/client/conversation-viewer/conversation-viewer.vala
@@ -156,7 +156,7 @@ public class ConversationViewer : Gtk.Stack, Geary.BaseInterface {
             // XXX move the ConversationListView management code into
             // MainWindow or somewhere more appropriate
             ConversationListView conversation_list = main_window.conversation_list_view;
-            this.selection_while_composing = conversation_list.get_selected_conversations();
+            this.selection_while_composing = conversation_list.copy_selected();
             conversation_list.get_selection().unselect_all();
 
             box.vanished.connect(on_composer_closed);
diff --git a/src/client/conversation-viewer/conversation-web-view.vala b/src/client/conversation-viewer/conversation-web-view.vala
index 217528ab..d22a836e 100644
--- a/src/client/conversation-viewer/conversation-web-view.vala
+++ b/src/client/conversation-viewer/conversation-web-view.vala
@@ -132,7 +132,7 @@ public class ConversationWebView : ClientWebView {
             });
 
         controller.search(
-            Geary.Collection.get_first(terms),
+            Geary.Collection.first(terms),
             WebKit.FindOptions.CASE_INSENSITIVE |
             WebKit.FindOptions.WRAP_AROUND,
             128
diff --git a/src/client/sidebar/sidebar-tree.vala b/src/client/sidebar/sidebar-tree.vala
index fdcd570b..e01103ab 100644
--- a/src/client/sidebar/sidebar-tree.vala
+++ b/src/client/sidebar/sidebar-tree.vala
@@ -766,17 +766,6 @@ public class Sidebar.Tree : Gtk.TreeView {
         store.set(iter, Columns.ICON, icon);
     }
 
-    private void load_branch_icons(Gtk.TreeIter iter) {
-        load_entry_icons(iter);
-
-        Gtk.TreeIter child_iter;
-        if (store.iter_children(out child_iter, iter)) {
-            do {
-                load_branch_icons(child_iter);
-            } while (store.iter_next(ref child_iter));
-        }
-    }
-
     private bool on_selection(Gtk.TreeSelection selection, Gtk.TreeModel model, Gtk.TreePath path,
         bool path_currently_selected) {
         // only allow selection if a page is selectable
diff --git a/src/engine/app/conversation-monitor/app-conversation-set.vala b/src/engine/app/conversation-monitor/app-conversation-set.vala
index ca626f6f..e9eb016a 100644
--- a/src/engine/app/conversation-monitor/app-conversation-set.vala
+++ b/src/engine/app/conversation-monitor/app-conversation-set.vala
@@ -302,7 +302,7 @@ private class Geary.App.ConversationSet : BaseObject {
         } else {
             Gee.Set<Conversation> associated =
                 get_associated_conversations(email);
-            conversation = Collection.get_first<Conversation>(associated);
+            conversation = Collection.first(associated);
             if (conversation == null) {
                 // Not in or related to any existing conversations, so
                 // create one
diff --git a/src/engine/app/email-store/app-copy-operation.vala b/src/engine/app/email-store/app-copy-operation.vala
index 44c76fd7..f6d37079 100644
--- a/src/engine/app/email-store/app-copy-operation.vala
+++ b/src/engine/app/email-store/app-copy-operation.vala
@@ -19,9 +19,9 @@ private class Geary.App.CopyOperation : Geary.App.AsyncFolderOperation {
         Geary.FolderSupport.Copy? copy = folder as Geary.FolderSupport.Copy;
         assert(copy != null);
 
-        Gee.List<Geary.EmailIdentifier> list
-            = Geary.Collection.to_array_list<Geary.EmailIdentifier>(ids);
-        yield copy.copy_email_async(list, destination, cancellable);
+        yield copy.copy_email_async(
+            Collection.copy(ids), destination, cancellable
+        );
         return ids;
     }
 }
diff --git a/src/engine/app/email-store/app-fetch-operation.vala b/src/engine/app/email-store/app-fetch-operation.vala
index eef93d10..4db6c457 100644
--- a/src/engine/app/email-store/app-fetch-operation.vala
+++ b/src/engine/app/email-store/app-fetch-operation.vala
@@ -20,7 +20,7 @@ private class Geary.App.FetchOperation : Geary.App.AsyncFolderOperation {
         Geary.Folder folder, Gee.Collection<Geary.EmailIdentifier> ids,
         Cancellable? cancellable) throws Error {
         assert(result == null);
-        Geary.EmailIdentifier? id = Geary.Collection.get_first(ids);
+        Geary.EmailIdentifier? id = Collection.first(ids);
         assert(id != null);
 
         result = yield folder.fetch_email_async(
diff --git a/src/engine/app/email-store/app-mark-operation.vala b/src/engine/app/email-store/app-mark-operation.vala
index f69b9049..00a0858c 100644
--- a/src/engine/app/email-store/app-mark-operation.vala
+++ b/src/engine/app/email-store/app-mark-operation.vala
@@ -21,9 +21,9 @@ private class Geary.App.MarkOperation : Geary.App.AsyncFolderOperation {
         Geary.FolderSupport.Mark? mark = folder as Geary.FolderSupport.Mark;
         assert(mark != null);
 
-        Gee.List<Geary.EmailIdentifier> list
-            = Geary.Collection.to_array_list<Geary.EmailIdentifier>(ids);
-        yield mark.mark_email_async(list, flags_to_add, flags_to_remove, cancellable);
+        yield mark.mark_email_async(
+            Collection.copy(ids), flags_to_add, flags_to_remove, cancellable
+        );
         return ids;
     }
 }
diff --git a/src/engine/imap-db/search/imap-db-search-folder.vala b/src/engine/imap-db/search/imap-db-search-folder.vala
index 5664b361..34e3ee71 100644
--- a/src/engine/imap-db/search/imap-db-search-folder.vala
+++ b/src/engine/imap-db/search/imap-db-search-folder.vala
@@ -319,8 +319,7 @@ private class Geary.ImapDB.SearchFolder : Geary.SearchFolder, Geary.FolderSuppor
                 yield folder.open_async(Geary.Folder.OpenFlags.NONE, cancellable);
                 open = true;
                 yield remove.remove_email_async(
-                    Geary.Collection.to_array_list<Geary.EmailIdentifier>(ids),
-                    cancellable
+                    Collection.copy(ids), cancellable
                 );
             } finally {
                 if (open) {
diff --git a/src/engine/imap-engine/replay-ops/imap-engine-create-email.vala b/src/engine/imap-engine/replay-ops/imap-engine-create-email.vala
index 9d519c47..51866395 100644
--- a/src/engine/imap-engine/replay-ops/imap-engine-create-email.vala
+++ b/src/engine/imap-engine/replay-ops/imap-engine-create-email.vala
@@ -73,7 +73,7 @@ private class Geary.ImapEngine.CreateEmail : SendReplayOperation {
                 );
 
             if (results.size > 0) {
-                this.created_id = Collection.get_first<Email>(results.keys).id;
+                this.created_id = Collection.first(results.keys).id;
             } else {
                 // Something went wrong creating/merging the message,
                 // so pretend we don't know what its UID is so the
diff --git a/src/engine/imap/api/imap-account-session.vala b/src/engine/imap/api/imap-account-session.vala
index ff335262..63838b2f 100644
--- a/src/engine/imap/api/imap-account-session.vala
+++ b/src/engine/imap/api/imap-account-session.vala
@@ -397,9 +397,13 @@ internal class Geary.Imap.AccountSession : Geary.Imap.SessionObject {
             cancellable
         );
 
-        assert(responses.size == 1);
-
-        return Geary.Collection.get_first(responses.values);
+        var response = Collection.first(responses.values);
+        if (response == null) {
+            throw new ImapError.SERVER_ERROR(
+                "No status response received from server"
+            );
+        }
+        return response;
     }
 
     private async Gee.Map<Command, StatusResponse>
diff --git a/src/engine/imap/api/imap-folder-session.vala b/src/engine/imap/api/imap-folder-session.vala
index 00f48ca8..d07199b2 100644
--- a/src/engine/imap/api/imap-folder-session.vala
+++ b/src/engine/imap/api/imap-folder-session.vala
@@ -688,7 +688,8 @@ private class Geary.Imap.FolderSession : Geary.Imap.SessionObject {
                 debug("Unable to retrieve COPYUID UIDs: %s", ierr.message);
             }
 
-            if (!Collection.is_empty(src_uids) && !Collection.is_empty(dst_uids)) {
+            if (src_uids != null && !src_uids.is_empty &&
+                dst_uids != null && !dst_uids.is_empty) {
                 Gee.Map<UID, UID> copyuids = new Gee.HashMap<UID, UID>();
                 int ctr = 0;
                 for (;;) {
diff --git a/src/engine/imap/transport/imap-client-session.vala b/src/engine/imap/transport/imap-client-session.vala
index d3ff645a..d26aef7a 100644
--- a/src/engine/imap/transport/imap-client-session.vala
+++ b/src/engine/imap/transport/imap-client-session.vala
@@ -1281,7 +1281,7 @@ public class Geary.Imap.ClientSession : BaseObject {
             check_unsupported_send_command(cmd);
 
         // only issue one event to the state machine for all commands; either all succeed or all fail
-        MachineParams params = new MachineParams(Geary.Collection.get_first(cmds));
+        MachineParams params = new MachineParams(Collection.first(cmds));
         fsm.issue(Event.SEND_CMD, null, params);
 
         if (params.err != null)
diff --git a/src/engine/rfc822/rfc822-mailbox-addresses.vala b/src/engine/rfc822/rfc822-mailbox-addresses.vala
index f218944f..616c28ab 100644
--- a/src/engine/rfc822/rfc822-mailbox-addresses.vala
+++ b/src/engine/rfc822/rfc822-mailbox-addresses.vala
@@ -184,19 +184,11 @@ public class Geary.RFC822.MailboxAddresses :
     }
 
     public bool equal_to(MailboxAddresses other) {
-        if (this == other)
-            return true;
-
-        if (addrs.size != other.addrs.size)
-            return false;
-
-        Gee.HashSet<RFC822.MailboxAddress> first = new Gee.HashSet<RFC822.MailboxAddress>();
-        first.add_all(addrs);
-
-        Gee.HashSet<RFC822.MailboxAddress> second = new Gee.HashSet<RFC822.MailboxAddress>();
-        second.add_all(other.addrs);
-
-        return Collection.are_sets_equal<RFC822.MailboxAddress>(first, second);
+        return (
+            this == other ||
+            (this.addrs.size == other.addrs.size &&
+             this.addrs.contains_all(other.addrs))
+        );
     }
 
     /**
diff --git a/src/engine/smtp/smtp-client-service.vala b/src/engine/smtp/smtp-client-service.vala
index 69071d00..70893b38 100644
--- a/src/engine/smtp/smtp-client-service.vala
+++ b/src/engine/smtp/smtp-client-service.vala
@@ -428,7 +428,7 @@ public class Geary.Smtp.ClientService : Geary.ClientService {
                     null, 1, REFERENCES, NONE, cancellable
                 );
                 if (list != null && !list.is_empty) {
-                    Email listed = Collection.get_first<Email>(list);
+                    Email listed = Collection.first(list);
                     if (listed.message_id != null &&
                         listed.message_id.equal_to(id)) {
                         break;
diff --git a/src/engine/util/util-collection.vala b/src/engine/util/util-collection.vala
index 0ba4e09e..4cf8316e 100644
--- a/src/engine/util/util-collection.vala
+++ b/src/engine/util/util-collection.vala
@@ -6,203 +6,164 @@
 
 namespace Geary.Collection {
 
-public delegate uint8 ByteTransformer(uint8 b);
+    public delegate uint8 ByteTransformer(uint8 b);
 
-public inline bool is_empty(Gee.Collection? c) {
-    return c == null || c.size == 0;
-}
 
-/** Returns a modifiable collection containing a single element. */
-public Gee.Collection<T> single<T>(T element) {
-    Gee.Collection<T> single = new Gee.LinkedList<T>();
-    single.add(element);
-    return single;
-}
-
-/** Returns a modifiable map containing a single entry. */
-public Gee.Map<K,V> single_map<K,V>(K key, V value) {
-    Gee.Map<K,V> single = new Gee.HashMap<K,V>();
-    single.set(key, value);
-    return single;
-}
-
-// A substitute for ArrayList<G>.wrap() for compatibility with older versions of Gee.
-public Gee.ArrayList<G> array_list_wrap<G>(G[] a, owned Gee.EqualDataFunc<G>? equal_func = null) {
-    Gee.ArrayList<G> list = new Gee.ArrayList<G>((owned) equal_func);
-    add_all_array<G>(list, a);
-    return list;
-}
-
-public Gee.ArrayList<G> to_array_list<G>(Gee.Collection<G> c) {
-    Gee.ArrayList<G> list = new Gee.ArrayList<G>();
-    list.add_all(c);
-
-    return list;
-}
-
-public Gee.HashMap<Key, Value> to_hash_map<Key, Value>(
-    Gee.Collection<Value> c, Gee.MapFunc<Key, Value> key_selector) {
-    Gee.HashMap<Key, Value> map = new Gee.HashMap<Key, Value>();
-    foreach (Value v in c)
-        map.set(key_selector(v), v);
-    return map;
-}
-
-public void add_all_array<G>(Gee.Collection<G> c, G[] ar) {
-    foreach (G g in ar)
-        c.add(g);
-}
-
-public G? get_first<G>(Gee.Collection<G> c) {
-    Gee.Iterator<G> iter = c.iterator();
-
-    return iter.next() ? iter.get() : null;
-}
-
-/**
- * Returns the first element in the Collection that passes the Predicte function.
- *
- * The Collection is walked in Iterator order.
- */
-public G? find_first<G>(Gee.Collection<G> c, owned Gee.Predicate<G> pred) {
-    Gee.Iterator<G> iter = c.iterator();
-    while (iter.next()) {
-        if (pred(iter.get()))
-            return iter.get();
+    /** Returns a modifiable collection containing a single element. */
+    public Gee.Collection<T> single<T>(T element) {
+        Gee.Collection<T> single = new Gee.LinkedList<T>();
+        single.add(element);
+        return single;
     }
 
-    return null;
-}
-
-public bool are_sets_equal<G>(Gee.Set<G> a, Gee.Set<G> b) {
-    if (a.size != b.size)
-        return false;
-
-    foreach (G element in a) {
-        if (!b.contains(element))
-            return false;
+    /** Returns a modifiable map containing a single entry. */
+    public Gee.Map<K,V> single_map<K,V>(K key, V value) {
+        Gee.Map<K,V> single = new Gee.HashMap<K,V>();
+        single.set(key, value);
+        return single;
     }
 
-    return true;
-}
-
-/**
- * Removes all elements from the Collection that do pass the Predicate function.
- *
- * Note that this modifies the supplied Collection.
- */
-public Gee.Collection<G> remove_if<G>(Gee.Collection<G> c, owned Gee.Predicate<G> pred) {
-    Gee.Iterator<G> iter = c.iterator();
-    while (iter.next()) {
-        if (pred(iter.get()))
-            iter.remove();
+    /** Returns a copy of the given collection in a new collection. */
+    public Gee.Collection<V> copy<V>(Gee.Collection<V> original) {
+        // Use a linked list, the returned value can't be accessed by
+        // index anyway
+        var copy = new Gee.LinkedList<V>();
+        copy.add_all(original);
+        return copy;
     }
 
-    return c;
-}
-
-/**
- * Sets the dest Map with all keys and values in src.
- */
-public void map_set_all<K, V>(Gee.Map<K, V> dest, Gee.Map<K, V> src) {
-    foreach (K key in src.keys)
-        dest.set(key, src.get(key));
-}
-
-/**
- * Sets multiple elements with the same key in a MultiMap.
- */
-public void multi_map_set_all<K, V>(Gee.MultiMap<K, V> dest, K key, Gee.Collection<V> values) {
-    foreach (V value in values)
-        dest.set(key, value);
-}
-
-/**
- * Removes all keys from the Map.
- */
-public void map_unset_all_keys<K, V>(Gee.Map<K, V> map, Gee.Collection<K> keys) {
-    foreach (K key in keys)
-        map.unset(key);
-}
-
-/**
- * Return a MultiMap of value => key of the input map's key => values.
- */
-public Gee.MultiMap<V, K> reverse_multi_map<K, V>(Gee.MultiMap<K, V> map) {
-    Gee.HashMultiMap<V, K> reverse = new Gee.HashMultiMap<V, K>();
-    foreach (K key in map.get_keys()) {
-        foreach (V value in map.get(key))
-            reverse.set(value, key);
+    /** Returns the first element from a collection. */
+    public G? first<G>(Gee.Collection<G> c) {
+        Gee.Iterator<G> iter = c.iterator();
+        return iter.next() ? iter.get() : null;
     }
 
-    return reverse;
-}
-
-/**
- * To be used by a Hashable's to_hash() method.
- */
-public inline uint int64_hash(int64 value) {
-    return hash_memory(&value, sizeof(int64));
-}
-
-/**
- * To be used as hash_func for Gee collections.
- */
-public inline uint int64_hash_func(int64? n) {
-    return hash_memory((uint8 *) n, sizeof(int64));
-}
-
-/**
- * To be used as equal_func for Gee collections.
- */
-public bool int64_equal_func(int64? a, int64? b) {
-    int64 *bia = (int64 *) a;
-    int64 *bib = (int64 *) b;
-
-    return (*bia) == (*bib);
-}
-
-/**
- * A rotating-XOR hash that can be used to hash memory buffers of any size.
- */
-public uint hash_memory(void *ptr, size_t bytes) {
-    if (ptr == null || bytes == 0)
-        return 0;
-
-    uint8 *u8 = (uint8 *) ptr;
-
-    // initialize hash to first byte value and then rotate-XOR from there
-    uint hash = *u8;
-    for (int ctr = 1; ctr < bytes; ctr++)
-        hash = (hash << 4) ^ (hash >> 28) ^ (*u8++);
-
-    return hash;
-}
-
-/**
- * A rotating-XOR hash that can be used to hash memory buffers of any size until a terminator byte
- * is found.
- *
- * A {@link ByteTransformer} may be supplied to convert bytes before they are hashed.
- *
- * Returns zero if the initial byte is the terminator.
- */
-public uint hash_memory_stream(void *ptr, uint8 terminator, ByteTransformer? cb) {
-    uint8 *u8 = (uint8 *) ptr;
-
-    uint hash = 0;
-    for (;;) {
-        uint8 b = *u8++;
-        if (b == terminator)
-            break;
-
-        if (cb != null)
-            b = cb(b);
-
-        hash = (hash << 4) ^ (hash >> 28) ^ b;
+    /**
+     * Removes all elements that pass the given predicate.
+     *
+     * Note that this modifies the supplied Collection.
+     */
+    public Gee.Collection<G> remove_if<G>(Gee.Collection<G> c,
+                                          owned Gee.Predicate<G> pred) {
+        Gee.Iterator<G> iter = c.iterator();
+        while (iter.next()) {
+            if (pred(iter.get())) {
+                iter.remove();
+            }
+        }
+        return c;
     }
 
-    return hash;
-}
+    /**
+     * Sets the dest Map with all keys and values in src.
+     */
+    public void map_set_all<K, V>(Gee.Map<K, V> dest, Gee.Map<K, V> src) {
+        foreach (K key in src.keys) {
+            dest.set(key, src.get(key));
+        }
+    }
+
+    /**
+     * Sets multiple elements with the same key in a MultiMap.
+     */
+    public void multi_map_set_all<K, V>(Gee.MultiMap<K, V> dest, K key, Gee.Collection<V> values) {
+        foreach (V value in values) {
+            dest.set(key, value);
+        }
+    }
+
+    /**
+     * Removes all keys from the Map.
+     */
+    public void map_unset_all_keys<K, V>(Gee.Map<K, V> map, Gee.Collection<K> keys) {
+        foreach (K key in keys) {
+            map.unset(key);
+        }
+    }
+
+    /**
+     * Return a MultiMap of value => key of the input map's key => values.
+     */
+    public Gee.MultiMap<V, K> reverse_multi_map<K, V>(Gee.MultiMap<K, V> map) {
+        Gee.HashMultiMap<V, K> reverse = new Gee.HashMultiMap<V, K>();
+        foreach (K key in map.get_keys()) {
+            foreach (V value in map.get(key)) {
+                reverse.set(value, key);
+            }
+        }
+
+        return reverse;
+    }
+
+    /**
+     * To be used by a Hashable's to_hash() method.
+     */
+    public inline uint int64_hash(int64 value) {
+        return hash_memory(&value, sizeof(int64));
+    }
+
+    /**
+     * To be used as hash_func for Gee collections.
+     */
+    public inline uint int64_hash_func(int64? n) {
+        return hash_memory((uint8 *) n, sizeof(int64));
+    }
+
+    /**
+     * To be used as equal_func for Gee collections.
+     */
+    public bool int64_equal_func(int64? a, int64? b) {
+        int64 *bia = (int64 *) a;
+        int64 *bib = (int64 *) b;
+
+        return (*bia) == (*bib);
+    }
+
+    /**
+     * A rotating-XOR hash that can be used to hash memory buffers of any size.
+     */
+    public uint hash_memory(void *ptr, size_t bytes) {
+        if (ptr == null || bytes == 0) {
+            return 0;
+        }
+
+        uint8 *u8 = (uint8 *) ptr;
+
+        // initialize hash to first byte value and then rotate-XOR from there
+        uint hash = *u8;
+        for (int ctr = 1; ctr < bytes; ctr++) {
+            hash = (hash << 4) ^ (hash >> 28) ^ (*u8++);
+        }
+
+        return hash;
+    }
+
+    /**
+     * A rotating-XOR hash that can be used to hash memory buffers of any size until a terminator byte
+     * is found.
+     *
+     * A {@link ByteTransformer} may be supplied to convert bytes before they are hashed.
+     *
+     * Returns zero if the initial byte is the terminator.
+     */
+    public uint hash_memory_stream(void *ptr, uint8 terminator, ByteTransformer? cb) {
+        uint8 *u8 = (uint8 *) ptr;
+
+        uint hash = 0;
+        for (;;) {
+            uint8 b = *u8++;
+            if (b == terminator) {
+                break;
+            }
+
+            if (cb != null) {
+                b = cb(b);
+            }
+
+            hash = (hash << 4) ^ (hash >> 28) ^ b;
+        }
+
+        return hash;
+    }
 
 }
diff --git a/src/engine/util/util-config-file.vala b/src/engine/util/util-config-file.vala
index 61ced4c4..6b938285 100644
--- a/src/engine/util/util-config-file.vala
+++ b/src/engine/util/util-config-file.vala
@@ -126,20 +126,20 @@ public class Geary.ConfigFile {
         }
 
         public Gee.List<string> get_string_list(string key) {
+            var strs = new Gee.ArrayList<string>();
             try {
-                string[] list = this.backing.get_string_list(this.name, key);
-                if (list.length > 0)
-                    return Geary.Collection.array_list_wrap<string>(list);
+                strs.add_all_array(this.backing.get_string_list(this.name, key));
             } catch (GLib.KeyFileError err) {
                 // Oh well
             }
-            return new Gee.ArrayList<string>();
+            return strs;
         }
 
         public Gee.List<string> get_required_string_list(string key)
             throws GLib.KeyFileError {
-            string[] list = this.backing.get_string_list(this.name, key);
-            return Geary.Collection.array_list_wrap<string>(list);
+            var strs = new Gee.ArrayList<string>();
+            strs.add_all_array(this.backing.get_string_list(this.name, key));
+            return strs;
         }
 
         public void set_string_list(string key, Gee.List<string> value) {
diff --git a/src/engine/util/util-iterable.vala b/src/engine/util/util-iterable.vala
index 2cff4b16..29ff8e27 100644
--- a/src/engine/util/util-iterable.vala
+++ b/src/engine/util/util-iterable.vala
@@ -20,7 +20,9 @@ namespace Geary {
         va_list args = va_list();
         G arg = g;
 
-        Gee.ArrayList<G> list = new Gee.ArrayList<G>();
+        // Use a linked list since we will only ever be iterating over
+        // it
+        var list = new Gee.LinkedList<G>();
         do {
             list.add(arg);
         } while((arg = args.arg()) != null);
@@ -31,8 +33,12 @@ namespace Geary {
     /**
      * Take an array of items and return a Geary.Iterable for convenience.
      */
-    public Geary.Iterable<G> iterate_array<G>(G[] a) {
-        return Geary.traverse<G>(Geary.Collection.array_list_wrap<G>(a));
+    public Geary.Iterable<G> iterate_array<G>(G[] a, owned Gee.EqualDataFunc<G>? equal_func = null) {
+        // Use a linked list since we will only ever be iterating over
+        // it
+        var list = new Gee.LinkedList<G>((owned) equal_func);
+        list.add_all_array(a);
+        return Geary.traverse<G>(list);
     }
 }
 
diff --git a/src/engine/util/util-object.vala b/src/engine/util/util-object.vala
index 2bbc0dd8..071da6f1 100644
--- a/src/engine/util/util-object.vala
+++ b/src/engine/util/util-object.vala
@@ -12,12 +12,10 @@ namespace Geary.ObjectUtils {
 public Gee.List<Binding>? mirror_properties(Object source, Object dest, BindingFlags
     flags = GLib.BindingFlags.DEFAULT | GLib.BindingFlags.SYNC_CREATE) {
     // Make sets of both object's properties.
-    Gee.HashSet<ParamSpec> source_properties = new Gee.HashSet<ParamSpec>();
-    Collection.add_all_array<ParamSpec>(source_properties,
-        source.get_class().list_properties());
-    Gee.HashSet<ParamSpec> dest_properties = new Gee.HashSet<ParamSpec>();
-    Collection.add_all_array<ParamSpec>(dest_properties,
-        dest.get_class().list_properties());
+    Gee.HashSet<ParamSpec> source_properties =
+        iterate_array(source.get_class().list_properties()).to_hash_set();
+    Gee.HashSet<ParamSpec> dest_properties =
+        iterate_array(dest.get_class().list_properties()).to_hash_set();
 
     // Remove properties from source_properties that are not in both sets.
     source_properties.retain_all(dest_properties);
diff --git a/test/engine/app/app-conversation-monitor-test.vala b/test/engine/app/app-conversation-monitor-test.vala
index 3d10684e..b38ad0a3 100644
--- a/test/engine/app/app-conversation-monitor-test.vala
+++ b/test/engine/app/app-conversation-monitor-test.vala
@@ -133,7 +133,7 @@ class Geary.App.ConversationMonitorTest : TestCase {
         assert_non_null(monitor.window_lowest, "Lowest window id");
         assert_equal(e1.id, monitor.window_lowest, "Lowest window id");
 
-        Conversation c1 = Geary.Collection.get_first(monitor.read_only_view);
+        Conversation c1 = Collection.first(monitor.read_only_view);
         assert_equal(e1, c1.get_email_by_id(e1.id), "Email not present in conversation");
     }
 
@@ -175,7 +175,7 @@ class Geary.App.ConversationMonitorTest : TestCase {
         assert_non_null(monitor.window_lowest, "Lowest window id");
         assert_equal(e2.id, monitor.window_lowest, "Lowest window id");
 
-        Conversation c1 = Geary.Collection.get_first(monitor.read_only_view);
+        Conversation c1 = Collection.first(monitor.read_only_view);
         assert_equal(e1, c1.get_email_by_id(e1.id), "Related email not present in conversation");
         assert_equal(e2, c1.get_email_by_id(e2.id), "In folder not present in conversation");
     }
@@ -329,7 +329,7 @@ class Geary.App.ConversationMonitorTest : TestCase {
 
         assert_int(1, monitor.size, "Conversation count");
 
-        Conversation c1 = Geary.Collection.get_first(monitor.read_only_view);
+        Conversation c1 = Collection.first(monitor.read_only_view);
         assert_int(2, c1.get_count(), "Conversation message count");
         assert_equal(e3, c1.get_email_by_id(e3.id),
                      "Appended email not present in conversation");
diff --git a/test/engine/app/app-conversation-set-test.vala b/test/engine/app/app-conversation-set-test.vala
index 29ac6512..1b3dc97b 100644
--- a/test/engine/app/app-conversation-set-test.vala
+++ b/test/engine/app/app-conversation-set-test.vala
@@ -116,7 +116,7 @@ class Geary.App.ConversationSetTest : TestCase {
         assert(this.test.get_email_count() == 1);
 
         assert(added.size == 1);
-        assert(Geary.Collection.get_first(added).get_email_by_id(e1.id) == e1);
+        assert(Collection.first(added).get_email_by_id(e1.id) == e1);
 
         assert(appended.size == 0);
         assert(removed.is_empty);
@@ -165,7 +165,7 @@ class Geary.App.ConversationSetTest : TestCase {
 
         assert(added.size == 1);
 
-        Conversation convo1 = Geary.Collection.get_first(added);
+        Conversation convo1 = Collection.first(added);
         assert(convo1.get_email_by_id(e1.id) == e1);
         assert(convo1.get_email_by_id(e2.id) == e2);
 
@@ -195,7 +195,7 @@ class Geary.App.ConversationSetTest : TestCase {
         assert(added.is_empty);
 
         assert(appended.size == 1);
-        Conversation convo2 = Geary.Collection.get_first(appended.get_keys());
+        Conversation convo2 = Collection.first(appended.get_keys());
         assert(convo2.get_email_by_id(e1.id) == e1);
         assert(convo2.get_email_by_id(e2.id) == e2);
         assert(convo2.get_email_by_id(e3.id) == e3);
@@ -234,7 +234,7 @@ class Geary.App.ConversationSetTest : TestCase {
         assert(added.is_empty);
 
         assert(appended.size == 1);
-        Conversation convo = Geary.Collection.get_first(appended.get_keys());
+        Conversation convo = Collection.first(appended.get_keys());
         assert(convo.get_email_by_id(e1.id) == e1);
         assert(convo.get_email_by_id(e2.id) == e2);
 
diff --git a/test/engine/common/common-contact-harvester-test.vala b/test/engine/common/common-contact-harvester-test.vala
index 02bc73d0..e73ccedf 100644
--- a/test/engine/common/common-contact-harvester-test.vala
+++ b/test/engine/common/common-contact-harvester-test.vala
@@ -73,7 +73,7 @@ class Geary.ContactHarvesterImplTest : TestCase {
 
         Gee.Collection<Contact> contacts = update_call.called_arg<Gee.Collection<Contact>>(0);
         assert_int(1, contacts.size, "contacts length");
-        Contact? created = Collection.get_first<Contact>(contacts) as Contact;
+        Contact? created = Collection.first(contacts) as Contact;
         assert_non_null(created, "contacts contents");
 
         assert_string("Test", created.real_name);
@@ -121,7 +121,7 @@ class Geary.ContactHarvesterImplTest : TestCase {
         this.store.assert_expectations();
 
         Gee.Collection<Contact> contacts = update_call.called_arg<Gee.Collection<Contact>>(0);
-        Contact? created = Collection.get_first<Contact>(contacts) as Contact;
+        Contact? created = Collection.first(contacts) as Contact;
         assert_int(
             Contact.Importance.SEEN,
             created.highest_importance,
@@ -150,7 +150,7 @@ class Geary.ContactHarvesterImplTest : TestCase {
         this.store.assert_expectations();
 
         Gee.Collection<Contact> contacts = update_call.called_arg<Gee.Collection<Contact>>(0);
-        Contact? created = Collection.get_first<Contact>(contacts) as Contact;
+        Contact? created = Collection.first(contacts) as Contact;
         assert_int(
             Contact.Importance.SENT_TO,
             created.highest_importance,
@@ -179,7 +179,7 @@ class Geary.ContactHarvesterImplTest : TestCase {
         this.store.assert_expectations();
 
         Gee.Collection<Contact> contacts = update_call.called_arg<Gee.Collection<Contact>>(0);
-        Contact? created = Collection.get_first<Contact>(contacts) as Contact;
+        Contact? created = Collection.first(contacts) as Contact;
         assert_int(
             Contact.Importance.RECEIVED_FROM,
             created.highest_importance,
diff --git a/test/engine/common/common-contact-store-impl-test.vala b/test/engine/common/common-contact-store-impl-test.vala
index 3974c00f..2bc50dea 100644
--- a/test/engine/common/common-contact-store-impl-test.vala
+++ b/test/engine/common/common-contact-store-impl-test.vala
@@ -125,7 +125,7 @@ class Geary.ContactStoreImplTest : TestCase {
         );
         assert_int(1, results.size, "results.size");
 
-        Contact search_hit = Collection.get_first(results);
+        Contact search_hit = Collection.first(results);
         assert_string("Test@example.com", search_hit.email, "Existing email");
         assert_string("test@example.com", search_hit.normalized_email, "Existing normalized_email");
         assert_string("Test Name", search_hit.real_name, "Existing real_name");
@@ -146,7 +146,7 @@ class Geary.ContactStoreImplTest : TestCase {
         );
         assert_int(1, results.size, "results.size");
 
-        Contact search_hit = Collection.get_first(results);
+        Contact search_hit = Collection.first(results);
         assert_string("Test@example.com", search_hit.email, "Existing email");
         assert_string("test@example.com", search_hit.normalized_email, "Existing normalized_email");
         assert_string("Test Name", search_hit.real_name, "Existing real_name");
@@ -180,7 +180,7 @@ class Geary.ContactStoreImplTest : TestCase {
         );
         assert_int(1, results.size, "results.size");
 
-        Contact search_hit = Collection.get_first(results);
+        Contact search_hit = Collection.first(results);
         assert_string("Germán", search_hit.real_name, "Existing real_name");
     }
 
@@ -211,7 +211,7 @@ class Geary.ContactStoreImplTest : TestCase {
         );
         assert_int(1, results.size, "results.size");
 
-        Contact search_hit = Collection.get_first(results);
+        Contact search_hit = Collection.first(results);
         assert_string("年収1億円目指せ", search_hit.real_name, "Existing real_name");
     }
 
diff --git a/test/engine/rfc822-mailbox-addresses-test.vala b/test/engine/rfc822-mailbox-addresses-test.vala
index 6c3a59b1..a9b2415e 100644
--- a/test/engine/rfc822-mailbox-addresses-test.vala
+++ b/test/engine/rfc822-mailbox-addresses-test.vala
@@ -12,6 +12,7 @@ class Geary.RFC822.MailboxAddressesTest : TestCase {
         add_test("from_rfc822_string_encoded", from_rfc822_string_encoded);
         add_test("from_rfc822_string_quoted", from_rfc822_string_quoted);
         add_test("to_rfc822_string", to_rfc822_string);
+        add_test("equal_to", equal_to);
     }
 
     public void from_rfc822_string_encoded() throws Error {
@@ -49,6 +50,38 @@ class Geary.RFC822.MailboxAddressesTest : TestCase {
                .to_rfc822_string() == "test1@example.com, test2@example.com");
     }
 
+    public void equal_to() throws Error {
+        var mailboxes_a = new_addreses({ "test1@example.com" });
+        var mailboxes_b = new_addreses({ "test1@example.com" });
+        var mailboxes_c = new_addreses({ "test2@example.com" });
+
+        assert_true(mailboxes_a.equal_to(mailboxes_a));
+        assert_true(mailboxes_a.equal_to(mailboxes_b));
+        assert_false(mailboxes_a.equal_to(mailboxes_c));
+
+        assert_true(
+            new_addreses({ "test1@example.com", "test2@example.com" }).equal_to(
+                new_addreses({ "test1@example.com", "test2@example.com" })
+            )
+        );
+        assert_true(
+            new_addreses({ "test1@example.com", "test2@example.com" }).equal_to(
+                new_addreses({ "test2@example.com", "test1@example.com" })
+            )
+        );
+
+        assert_false(
+            new_addreses({ "test1@example.com", "test2@example.com" }).equal_to(
+                new_addreses({ "test1@example.com" })
+            )
+        );
+        assert_false(
+            new_addreses({ "test1@example.com", "test2@example.com" }).equal_to(
+                new_addreses({ "test1@example.com", "test3@example.com" })
+            )
+        );
+    }
+
     private MailboxAddresses new_addreses(string[] address_strings) {
         Gee.List<MailboxAddress> addresses = new Gee.LinkedList<MailboxAddress>();
         foreach (string address in address_strings) {