diff --git a/clean.sh b/clean.sh
index 5c4a6d5..59325f2 100755
--- a/clean.sh
+++ b/clean.sh
@@ -5,6 +5,6 @@ set -e -u -o pipefail
 rm -rf frontend/node_modules/
 rm -rf backend/node_modules/
 rm -f ucs-*.tar.gz
-rm -r ucs
+rm -rf ucs
 
 echo "Cleaned."