diff --git a/src/server/index.js b/src/server/index.js
index b92240d..06ad467 100644
--- a/src/server/index.js
+++ b/src/server/index.js
@@ -250,6 +250,8 @@ const processKeyData = (keyData) => {
     })
   })
 
+  keyData.primaryUserIndex ||= 0
+
   return keyData
 }