diff --git a/scripts/process_subways.sh b/scripts/process_subways.sh
index e6dbe9e..ec68d42 100755
--- a/scripts/process_subways.sh
+++ b/scripts/process_subways.sh
@@ -89,5 +89,5 @@ rm "$VALIDATION"
 
 if [ -n "${SERVER-}" ]; then
   scp -q ${SERVER_KEY+-i "$SERVER_KEY"} "$HTML_DIR"/* "$SERVER"
-  [ -n "$REMOVE_HTML" ] && rm -r "$HTML_DIR"
+  [ -n "${REMOVE_HTML-}" ] && rm -r "$HTML_DIR"
 fi