diff --git a/diff-sha.sh b/diff-sha.sh
index 26f8bcc3..c0fc1b2a 100644
--- a/diff-sha.sh
+++ b/diff-sha.sh
@@ -61,6 +61,7 @@ if [[ -z $GITHUB_EVENT_PULL_REQUEST_BASE_REF ]]; then
     echo "Fetching remote refs..."
     # shellcheck disable=SC2086
     git fetch $EXTRA_ARGS -u --progress --deepen="$INPUT_FETCH_DEPTH" origin +refs/heads/"$CURRENT_BRANCH":refs/remotes/origin/"$CURRENT_BRANCH" 1>/dev/null
+    git submodule update --recursive || true
   fi
 
   echo "::debug::Getting HEAD SHA..."