diff --git a/pkg/socket/socket.go b/pkg/socket/socket.go
index d445fe6..f66294f 100644
--- a/pkg/socket/socket.go
+++ b/pkg/socket/socket.go
@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build !appengine
+
 // Package socket implements an WebSocket-based playground backend.
 // Clients connect to a websocket handler and send run/kill commands, and
 // the server sends the output and exit status of the running processes.