diff --git a/parts/packages.nix b/parts/packages.nix
index 7608829..0644068 100644
--- a/parts/packages.nix
+++ b/parts/packages.nix
@@ -37,10 +37,10 @@
         ];
         text = ''
           start_dir="$PWD"
-          if [ -n "${GITEA_WORKSPACE:-}" ]; then
-            cd "$GITEA_WORKSPACE"
-          elif [ -n "${GITHUB_WORKSPACE:-}" ]; then
-            cd "$GITHUB_WORKSPACE"
+          if [ -n "''${GITEA_WORKSPACE:-}" ]; then
+            cd "''${GITEA_WORKSPACE}"
+          elif [ -n "''${GITHUB_WORKSPACE:-}" ]; then
+            cd "''${GITHUB_WORKSPACE}"
           fi
           while [ ! -x ./scripts/mcp-server/run-tests.sh ]; do
             if [ "$PWD" = "/" ]; then