diff --git a/add_extension.sh b/add_extension.sh
index 245d114..9a24a3e 100644
--- a/add_extension.sh
+++ b/add_extension.sh
@@ -17,4 +17,6 @@ if [[ "${EXT_VERSION}" ]]; then
     git checkout -b "${EXT_VERSION}" "origin/${EXT_VERSION}"
 fi
 
-composer install --no-dev
+if [[ -e "composer.json" ]]; then
+    composer install --no-dev
+fi