diff --git a/src/main/java/com/recom/observer/Subject.java b/src/main/java/com/recom/observer/Subject.java
index 2cc97f49..e36d6876 100644
--- a/src/main/java/com/recom/observer/Subject.java
+++ b/src/main/java/com/recom/observer/Subject.java
@@ -23,7 +23,9 @@ public void observationStoppedThrough(final @NonNull Observing<T> observer) {
 
     @Override
     public void notifyObserversWith(@NonNull final Notification<T> notification) {
-        observersWatchingMe.forEach(observer -> observer.takeNotice(this, notification));
+        // run through a copy of the list to avoid ConcurrentModificationException when removing observers!
+        final List<Observing<T>> copiedObserversWatchingMe = new ArrayList<>(observersWatchingMe);
+        copiedObserversWatchingMe.forEach(observer -> observer.takeNotice(this, notification));
     }
 
     @Override
diff --git a/src/main/java/com/recom/service/messagebus/MessageLongPollObserver.java b/src/main/java/com/recom/service/messagebus/MessageLongPollObserver.java
index e1f853e7..3dc16254 100644
--- a/src/main/java/com/recom/service/messagebus/MessageLongPollObserver.java
+++ b/src/main/java/com/recom/service/messagebus/MessageLongPollObserver.java
@@ -67,6 +67,7 @@ public void takeNotice(
             responseBodyEmitter.completeWithError(e);
         } finally {
             responseBodyEmitter.complete();
+            subject.observationStoppedThrough(this);
         }
     }