diff --git a/actionpack/lib/action_dispatch/middleware/show_exceptions.rb b/actionpack/lib/action_dispatch/middleware/show_exceptions.rb
index 108355da6310a0b66af5937fe38dea3059857340..4d598669c737ad8bfaaa60f477da860fcc4f54ed 100644
--- a/actionpack/lib/action_dispatch/middleware/show_exceptions.rb
+++ b/actionpack/lib/action_dispatch/middleware/show_exceptions.rb
@@ -102,7 +102,7 @@ def status_code(exception)
       end
 
       def render(status, body)
-        [status, {'Content-Type' => 'text/html', 'Content-Length' => body.length.to_s}, body]
+        [status, {'Content-Type' => 'text/html', 'Content-Length' => body.length.to_s}, [body]]
       end
 
       def public_path