--- a/editor/libeditor/TextEditor.cpp
+++ b/editor/libeditor/TextEditor.cpp
@@ -872,24 +872,24 @@ TextEditor::UpdateIMEComposition(WidgetC
   //       of NotifiyEditorObservers(eNotifyEditorObserversOfEnd) or
   //       NotifiyEditorObservers(eNotifyEditorObserversOfCancel) which notifies
   //       TextComposition of a selection change.
   MOZ_ASSERT(!mPlaceholderBatch,
     "UpdateIMEComposition() must be called without place holder batch");
   TextComposition::CompositionChangeEventHandlingMarker
     compositionChangeEventHandlingMarker(mComposition, aCompsitionChangeEvent);
 
-  NotifyEditorObservers(eNotifyEditorObserversOfBefore);
-
   RefPtr<nsCaret> caretP = ps->GetCaret();
 
   nsresult rv;
   {
     AutoPlaceHolderBatch batch(this, nsGkAtoms::IMETxnName);
 
+    MOZ_ASSERT(mIsInEditAction,
+      "AutoPlaceHolderBatch should've notified the observes of before-edit");
     rv = InsertText(aCompsitionChangeEvent->mData);
 
     if (caretP) {
       caretP->SetSelection(selection);
     }
   }
 
   // If still composing, we should fire input event via observer.