diff --git a/src/providers/core/oai-response.ts b/src/providers/core/oai-response.ts
index 1112ab3..ad26a34 100644
--- a/src/providers/core/oai-response.ts
+++ b/src/providers/core/oai-response.ts
@@ -42,7 +42,7 @@ const responseTemplate = {
         {
             _attr:
                 {
-                    xmlns: 'http://www.openarchives.org/OAI/2.0/',
+                    'xmlns': 'http://www.openarchives.org/OAI/2.0/',
                     'xmlns:xsi': 'http://www.w3.org/2001/XMLSchema-instance',
                     'xmlns:dc': 'http://purl.org/dc/elements/1.1/',
                     'xsi:schemaLocation': 'http://www.openarchives.org/OAI/2.0/ ' +