--- a/dom/events/IMEStateManager.cpp
+++ b/dom/events/IMEStateManager.cpp
@@ -261,16 +261,27 @@ IMEStateManager::NotifyIMEOfBlurForChild
      sFocusedIMETabParent.get(), sFocusedIMEWidget));
 
   if (!sFocusedIMETabParent) {
     MOZ_ASSERT(!sFocusedIMEWidget);
     return;
   }
 
   MOZ_ASSERT(sFocusedIMEWidget);
+
+  if (MOZ_LOG_TEST(sISMLog, LogLevel::Debug) && sTextCompositions) {
+    RefPtr<TextComposition> composition =
+      sTextCompositions->GetCompositionFor(sFocusedIMEWidget);
+    if (composition) {
+      MOZ_LOG(sISMLog, LogLevel::Debug,
+        ("  NotifyIMEOfBlurForChildProcess(), sFocusedIMEWidget still has "
+         "composition"));
+    }
+  }
+
   NotifyIME(NOTIFY_IME_OF_BLUR, sFocusedIMEWidget, sFocusedIMETabParent);
 
   MOZ_ASSERT(!sFocusedIMETabParent);
   MOZ_ASSERT(!sFocusedIMEWidget);
 }
 
 // static
 void
@@ -481,19 +492,22 @@ IMEStateManager::OnChangeFocusInternal(n
   // a native IME context is shared on all editors on some widgets or all
   // widgets (it depends on platforms).
   if (oldWidget && focusActuallyChanging && sTextCompositions) {
     RefPtr<TextComposition> composition =
       sTextCompositions->GetCompositionFor(oldWidget);
     if (composition) {
       // However, don't commit the composition if we're being inactivated
       // but the composition should be kept even during deactive.
+      // Note that oldWidget and sFocusedIMEWidget may be different here (in
+      // such case, sFocusedIMEWidget is perhaps nullptr).  For example, IME
+      // may receive only blur notification but still has composition.
+      // We need to clean up only the oldWidget's composition state here.
       if (aPresContext ||
-          !sFocusedIMEWidget->IMENotificationRequestsRef().
-           WantDuringDeactive()) {
+          !oldWidget->IMENotificationRequestsRef().WantDuringDeactive()) {
         MOZ_LOG(sISMLog, LogLevel::Info,
           ("  OnChangeFocusInternal(), requesting to commit composition to "
            "the (previous) focused widget"));
         NotifyIME(REQUEST_TO_COMMIT_COMPOSITION, oldWidget,
                   composition->GetTabParent());
       }
     }
   }