diff --git a/app/run_docker.sh b/app/run_docker.sh
index 547be6e3d..cd5364739 100755
--- a/app/run_docker.sh
+++ b/app/run_docker.sh
@@ -135,6 +135,15 @@ if [[ -n "$GIT_REPO_DIR" ]]; then
     DOCKER_ARGS+=( -v "$GIT_REPO_DIR/src:/src" )
   fi
 
+  # Prefer ./externals (plural) as requested; fall back to ./external
+  if [[ -d "$GIT_REPO_DIR/externals" ]]; then
+    DOCKER_ARGS+=( -v "$GIT_REPO_DIR/externals:/repo/external" )
+    echo "Mounting repo externals from $GIT_REPO_DIR/externals -> /repo/external"
+  elif [[ -d "$GIT_REPO_DIR/external" ]]; then
+    DOCKER_ARGS+=( -v "$GIT_REPO_DIR/external:/repo/external" )
+    echo "Mounting repo external from $GIT_REPO_DIR/external -> /repo/external"
+  fi
+
   if [[ -z "$WORKDIR_IN_CONTAINER" ]]; then
     WORKDIR_IN_CONTAINER="/repo"
   fi