diff --git a/incubator/store/src/main/java/org/onosproject/incubator/store/mcast/impl/MulticastData.java b/incubator/store/src/main/java/org/onosproject/incubator/store/mcast/impl/MulticastData.java
index 7bf4a10..0d2fa24 100644
--- a/incubator/store/src/main/java/org/onosproject/incubator/store/mcast/impl/MulticastData.java
+++ b/incubator/store/src/main/java/org/onosproject/incubator/store/mcast/impl/MulticastData.java
@@ -57,6 +57,7 @@
     }
 
     public void setSource(ConnectPoint source) {
+        // FIXME: violates immutability
         isEmpty.set(false);
         this.source.set(source);
     }