--- a/widget/cocoa/TextInputHandler.mm
+++ b/widget/cocoa/TextInputHandler.mm
@@ -2208,35 +2208,35 @@ TextInputHandler::InsertText(NSAttribute
       MOZ_LOG(gLog, LogLevel::Error,
         ("%p IMEInputHandler::HandleKeyUpEvent, "
          "FAILED, due to BeginNativeInputTransaction() failure", this));
     return;
   }
 
   // Dispatch keypress event with char instead of compositionchange event
   WidgetKeyboardEvent keypressEvent(true, eKeyPress, mWidget);
+  // XXX Why do we need to dispatch keypress event for not inputting any
+  //     string?  If it wants to delete the specified range, should we
+  //     dispatch an eContentCommandDelete event instead?  Because this
+  //     must not be caused by a key operation, a part of IME's processing.
   keypressEvent.mIsChar = IsPrintableChar(str.CharAt(0));
 
   // Don't set other modifiers from the current event, because here in
   // -insertText: they've already been taken into account in creating
   // the input string.
 
   if (currentKeyEvent) {
     NSEvent* keyEvent = currentKeyEvent->mKeyEvent;
     InitKeyEvent(keyEvent, keypressEvent, &str);
   } else {
     nsCocoaUtils::InitInputEvent(keypressEvent, static_cast<NSEvent*>(nullptr));
-    if (keypressEvent.mIsChar) {
-      keypressEvent.mCharCode = str.CharAt(0);
-    }
-    // Note that insertText is not called only at key pressing.
-    if (!keypressEvent.mCharCode) {
-      keypressEvent.mKeyCode =
-        WidgetUtils::ComputeKeyCodeFromChar(keypressEvent.mCharCode);
-    }
+    keypressEvent.mKeyNameIndex = KEY_NAME_INDEX_USE_STRING;
+    keypressEvent.mKeyValue = str;
+    // FYI: TextEventDispatcher will set mKeyCode to 0 for printable key's
+    //      keypress events even if they don't cause inputting non-empty string.
   }
 
   // Remove basic modifiers from keypress event because if they are included,
   // nsPlaintextEditor ignores the event.
   keypressEvent.mModifiers &= ~(MODIFIER_CONTROL |
                                 MODIFIER_ALT |
                                 MODIFIER_META);