diff --git a/spring-websocket/src/main/java/org/springframework/web/messaging/support/PubSubMessageBuilder.java b/spring-websocket/src/main/java/org/springframework/web/messaging/support/PubSubMessageBuilder.java
index 4e298a2427..33a14267ce 100644
--- a/spring-websocket/src/main/java/org/springframework/web/messaging/support/PubSubMessageBuilder.java
+++ b/spring-websocket/src/main/java/org/springframework/web/messaging/support/PubSubMessageBuilder.java
@@ -19,8 +19,7 @@ package org.springframework.web.messaging.support;
 import org.springframework.http.MediaType;
 import org.springframework.messaging.Message;
 import org.springframework.messaging.support.MessageBuilder;
-
-import reactor.util.Assert;
+import org.springframework.util.Assert;
 
 
 /**