diff --git a/lib/mini_profiler.rb b/lib/mini_profiler.rb
index 46743b11..9b9b201d 100644
--- a/lib/mini_profiler.rb
+++ b/lib/mini_profiler.rb
@@ -469,7 +469,7 @@ def inject(fragment, script)
           safe_script = script.html_safe
         end
 
-        fragment.insert(index, safe_script)
+        (+fragment).insert(index, safe_script)
       else
         fragment
       end