diff --git a/js/apps/system/users/setup.js b/js/apps/system/users/setup.js
index 84d9dc1128..707341ae48 100644
--- a/js/apps/system/users/setup.js
+++ b/js/apps/system/users/setup.js
@@ -7,4 +7,4 @@
   if (db._collection(usersName) === null) {
     db._create(usersName, {isSystem: true});
   }
-}());
\ No newline at end of file
+}());
diff --git a/js/server/modules/org/arangodb/foxx/manager.js b/js/server/modules/org/arangodb/foxx/manager.js
index 90d943a3db..8b344047e1 100644
--- a/js/server/modules/org/arangodb/foxx/manager.js
+++ b/js/server/modules/org/arangodb/foxx/manager.js
@@ -194,12 +194,15 @@ function extendContext (context, app, root) {
   var cp = context.collectionPrefix;
   var cname = "";
 
-  if (cp !== "") {
+  if (cp === "_") {
+    cname = "_";
+  }
+  else if (cp !== "") {
     cname = cp + "_";
   }
 
   context.collectionName = function (name) {
-    var replaced = (cname + name).replace(/[^a-zA-Z0-9]/g, '_').replace(/(^_+|_+$)/g, '').substr(0, 64);
+    var replaced = cname + name.replace(/[^a-zA-Z0-9]/g, '_').replace(/(^_+|_+$)/g, '').substr(0, 64);
 
     if (replaced.length === 0) {
       throw new Error("Cannot derive collection name from '" + name + "'");