diff --git a/org.gnome.Geary.json b/org.gnome.Geary.json
index e0768920..791c19f9 100644
--- a/org.gnome.Geary.json
+++ b/org.gnome.Geary.json
@@ -230,7 +230,7 @@
                 {
                     "type": "git",
                     "url": "https://github.com/Yeraze/ytnef.git",
-                    "branch": "master"
+                    "branch": "v1.9.3"
                 }
             ]
         },
diff --git a/org.gnome.Geary.yaml b/org.gnome.Geary.yaml
index 85449488..7a9acd5f 100644
--- a/org.gnome.Geary.yaml
+++ b/org.gnome.Geary.yaml
@@ -222,7 +222,9 @@ modules:
     sources:
       - type: git
         url: https://github.com/Yeraze/ytnef.git
-        branch: master
+        # Pin to last known good version while
+        # https://github.com/Yeraze/ytnef/issues/81 remains an issue
+        branch: v1.9.3
 
   # Geary dependency
   - name: sound-theme-freedesktop