--- a/ipc/mscom/VTableBuilder.h
+++ b/ipc/mscom/VTableBuilder.h
@@ -3,17 +3,17 @@
 /* This Source Code Form is subject to the terms of the Mozilla Public
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 #ifndef mozilla_mscom_VTableBuilder_h
 #define mozilla_mscom_VTableBuilder_h
 
 #include <stdint.h>
-#include <Unknwn.h>
+#include <unknwn.h>
 
 #if defined(__cplusplus)
 extern "C" {
 #endif
 
 /**
  * This function constructs an interface with |aVtblSize| entries, where the
  * IUnknown methods are valid and redirect to |aUnk|. Other than the IUnknown