diff --git a/src/TopicTree.h b/src/TopicTree.h
index 73eef97..a837128 100644
--- a/src/TopicTree.h
+++ b/src/TopicTree.h
@@ -252,6 +252,11 @@ public:
             /* This one always resets needsDrainage before it calls any cb's.
              * Otherwise we would stackoverflow when sending after publish but before drain. */
             drainImpl(s);
+            
+            /* If we drained last subscriber, also clear outgoingMessages */
+            if (!drainableSubscribers) {
+                outgoingMessages.clear();
+            }
         }
     }