diff --git a/lua/cmp/entry.lua b/lua/cmp/entry.lua
index 4a90741..088ad8b 100644
--- a/lua/cmp/entry.lua
+++ b/lua/cmp/entry.lua
@@ -248,7 +248,7 @@ entry.get_vim_item = function(self, suggest_offset)
     end
     vim_item.equal = 1
     vim_item.empty = 1
-    vim_item.user_data = { cmp = self.id }
+    vim_item.user_data = ('cmp:%s'):format(self.id)
 
     return vim_item
   end)