diff --git a/widget/windows/KeyboardLayout.cpp b/widget/windows/KeyboardLayout.cpp
index 3f23033a36d3..03b72f9ba0b7 100644
--- a/widget/windows/KeyboardLayout.cpp
+++ b/widget/windows/KeyboardLayout.cpp
@@ -1367,9 +1367,14 @@ NativeKey::GetFollowingCharMessage(MSG& aCharMsg) const
       continue;
     }
 
+    // NOTE: Although, we don't know when this case occurs, the scan code value
+    //       in lParam may be changed from 0 to something.  The changed value
+    //       is different from the scan code of handling keydown message.
+    static const LPARAM kScanCodeMask = 0x00FF0000;
     if (removedMsg.message != nextKeyMsg.message ||
         removedMsg.wParam != nextKeyMsg.wParam ||
-        removedMsg.lParam != nextKeyMsg.lParam) {
+        (removedMsg.lParam & ~kScanCodeMask) !=
+          (nextKeyMsg.lParam & ~kScanCodeMask)) {
 #ifdef MOZ_CRASHREPORTER
       nsPrintfCString info("\nHandling message: %s (0x%08X), wParam: 0x%08X, "
                            "lParam: 0x%08X, InSendMessageEx()=%s, \n"