diff --git a/src/main/java/org/java_websocket/server/WebSocketServer.java b/src/main/java/org/java_websocket/server/WebSocketServer.java
index ceba5da6..07c7417c 100644
--- a/src/main/java/org/java_websocket/server/WebSocketServer.java
+++ b/src/main/java/org/java_websocket/server/WebSocketServer.java
@@ -279,7 +279,9 @@ public void stop() throws IOException , InterruptedException {
 	 * @since 1.3.8
 	 */
 	public Collection<WebSocket> getConnections() {
-		return Collections.unmodifiableCollection( new ArrayList<WebSocket>(connections) );
+		synchronized (connections) {
+			return Collections.unmodifiableCollection( new ArrayList<WebSocket>(connections) );
+		}
 	}
 
 	public InetSocketAddress getAddress() {