--- a/taskcluster/docker/firefox-snap/runme.sh
+++ b/taskcluster/docker/firefox-snap/runme.sh
@@ -42,16 +42,22 @@ cp -v "$SCRIPT_DIRECTORY/firefox.desktop
 locales=$(python3 "$SCRIPT_DIRECTORY/extract_locales_from_l10n_json.py" "${WORKSPACE}/l10n_changesets.json")
 
 mkdir -p "$DISTRIBUTION_DIR/extensions"
 for locale in $locales; do
     $CURL -o "$SOURCE_DEST/distribution/extensions/langpack-${locale}@firefox.mozilla.org.xpi" \
         "$CANDIDATES_DIR/${VERSION}-candidates/build${BUILD_NUMBER}/linux-x86_64/xpi/${locale}.xpi"
 done
 
+# Extract gtk30.mo from Ubuntu language packs
+apt download language-pack-gnome-*-base
+for i in *.deb; do
+    dpkg-deb --fsys-tarfile $i |tar xv -C "$SOURCE_DEST" --wildcards "./usr/share/locale-langpack/*/LC_MESSAGES/gtk30.mo" || true
+done
+
 # Generate snapcraft manifest
 sed -e "s/@VERSION@/${VERSION}/g" -e "s/@BUILD_NUMBER@/${BUILD_NUMBER}/g" snapcraft.yaml.in > "${WORKSPACE}/snapcraft.yaml"
 cp -v "$SCRIPT_DIRECTORY/mime"{-handler.xml,apps.list} "$WORKSPACE"
 cd "${WORKSPACE}"
 snapcraft
 
 mv -- *.snap "$TARGET_FULL_PATH"
 

--- a/taskcluster/docker/firefox-snap/snapcraft.yaml.in
+++ b/taskcluster/docker/firefox-snap/snapcraft.yaml.in
@@ -47,18 +47,20 @@ parts:
       - libxt6
       - libdbus-glib-1-2
       - libasound2
       - libpulse0
       - libgl1-mesa-dri
       - libgl1-mesa-glx
       - libmirclient9
       - desktop-file-utils
+      - ffmpeg
       - xdg-utils
-      - ffmpeg
+      - libc-bin
+      - locales-all
     after: [desktop-gtk3]
 
   xdg-open:
     after: [firefox]
     plugin: nil
     source: .
     install: |
       set -eux