diff --git a/frontend-js/src/main/js/gui/admin/AddProjectDialog.js b/frontend-js/src/main/js/gui/admin/AddProjectDialog.js
index 6cbf712a76620ddacc9892132f3f62dccd195150..4d2999451332b528cc14989f03e609a3e39d748e 100644
--- a/frontend-js/src/main/js/gui/admin/AddProjectDialog.js
+++ b/frontend-js/src/main/js/gui/admin/AddProjectDialog.js
@@ -1174,14 +1174,14 @@ AddProjectDialog.prototype.createZipEntry = function (jsZipEntry, zipObject) {
   var type;
   var data = {};
   var processingPromise = Promise.resolve();
-  if (filename.startsWith("submaps")) {
+  if (filename.indexOf("submaps") === 0) {
     type = "MAP";
     if (filename.endsWith("mapping.xml")) {
       data.mapping = true;
     }
-  } else if (filename.startsWith("images")) {
+  } else if (filename.indexOf("images") === 0) {
     type = "IMAGE";
-  } else if (filename.startsWith("layouts") || filename.startsWith("overlays")) {
+  } else if (filename.indexOf("layouts") === 0 || filename.indexOf("overlays") === 0) {
     type = "OVERLAY";
     processingPromise = zipObject.file(jsZipEntry.name).async("string").then(function (content) {
       var overlayParser = new OverlayParser();