diff --git a/.update.sh b/.update.sh
index 1577b30..1f13374 100644
--- a/.update.sh
+++ b/.update.sh
@@ -25,7 +25,7 @@ if [[ "$(git rev-parse HEAD)" == "$dfs_commit" ]]; then
     post_log "INFO" "$THIS_FILE" "nothing to do"
 else
     fmt_info "checking out to commit $dfs_commit ..."
-    if [[ -z "DFS_DEV" ]]; then
+    if [[ -z "$DFS_DEV" ]]; then
         git -c advice.detachedHead=false checkout $dfs_commit
     else
         fmt_warning "won't really checkout in dev mode"