diff --git a/src/main/java/org/java_websocket/server/WebSocketServer.java b/src/main/java/org/java_websocket/server/WebSocketServer.java
index bb17fa4e9..62c618c09 100644
--- a/src/main/java/org/java_websocket/server/WebSocketServer.java
+++ b/src/main/java/org/java_websocket/server/WebSocketServer.java
@@ -254,7 +254,7 @@ public void stop( int timeout ) throws InterruptedException {
 
 		synchronized ( this ) {
 			if( selectorthread != null  ) {
-				selector.wakeup();
+				if(selector != null) selector.wakeup();
 				selectorthread.join( timeout );
 			}
 		}