diff --git a/Mage.Server/src/main/java/mage/server/ServerImpl.java b/Mage.Server/src/main/java/mage/server/ServerImpl.java
index ba474dfe3b..630e78c919 100644
--- a/Mage.Server/src/main/java/mage/server/ServerImpl.java
+++ b/Mage.Server/src/main/java/mage/server/ServerImpl.java
@@ -238,7 +238,10 @@ public class ServerImpl extends RemoteServer implements Server {
 				new Runnable() {
 					@Override
 					public void run() {
-						SessionManager.getInstance().getSession(sessionId).kill();
+						Session session = SessionManager.getInstance().getSession(sessionId);
+						if (session != null) {
+							session.kill();
+						}
 						logger.info("Client deregistered ...");
 					}
 				}