--- a/accessible/ipc/win/handler/HandlerDataCleanup.h
+++ b/accessible/ipc/win/handler/HandlerDataCleanup.h
@@ -2,17 +2,17 @@
 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
 /* 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_a11y_HandlerDataCleanup_h
 #define mozilla_a11y_HandlerDataCleanup_h
 
-#include <OleAuto.h>
+#include <oleauto.h>
 #include "HandlerData.h"
 
 namespace mozilla {
 namespace a11y {
 
 inline void
 ReleaseStaticIA2DataInterfaces(StaticIA2Data& aData)
 {

--- a/gfx/layers/d3d11/CompositorD3D11.cpp
+++ b/gfx/layers/d3d11/CompositorD3D11.cpp
@@ -30,21 +30,17 @@
 
 #include "mozilla/EnumeratedArray.h"
 #include "mozilla/Telemetry.h"
 #include "BlendShaderConstants.h"
 
 #include "D3D11ShareHandleImage.h"
 #include "DeviceAttachmentsD3D11.h"
 
-#ifdef __MINGW32__
 #include <versionhelpers.h> // For IsWindows8OrGreater
-#else
-#include <VersionHelpers.h> // For IsWindows8OrGreater
-#endif
 #include <winsdkver.h>
 
 namespace mozilla {
 
 using namespace gfx;
 
 namespace layers {
 

--- a/toolkit/crashreporter/minidump-analyzer/Win64ModuleUnwindMetadata.cpp
+++ b/toolkit/crashreporter/minidump-analyzer/Win64ModuleUnwindMetadata.cpp
@@ -6,17 +6,17 @@
 #if XP_WIN && HAVE_64BIT_BUILD
 
 #include "Win64ModuleUnwindMetadata.h"
 
 #include "MinidumpAnalyzerUtils.h"
 
 #include <windows.h>
 #include <winnt.h>
-#include <ImageHlp.h>
+#include <imagehlp.h>
 #include <iostream>
 #include <set>
 #include <sstream>
 #include <string>
 
 namespace CrashReporter {
 
 union UnwindCode {

--- a/toolkit/crashreporter/minidump-analyzer/Win64ModuleUnwindMetadata.h
+++ b/toolkit/crashreporter/minidump-analyzer/Win64ModuleUnwindMetadata.h
@@ -9,17 +9,17 @@
 #if XP_WIN && HAVE_64BIT_BUILD
 
 #include <functional>
 #include <map>
 #include <string>
 
 #include <windows.h>
 #include <winnt.h>
-#include <ImageHlp.h>
+#include <imagehlp.h>
 
 namespace CrashReporter {
 
 struct UnwindCFI
 {
   uint32_t beginAddress;
   uint32_t size;
   uint32_t stackSize;

--- a/tools/fuzzing/libfuzzer/FuzzerUtilWindows.cpp
+++ b/tools/fuzzing/libfuzzer/FuzzerUtilWindows.cpp
@@ -17,17 +17,17 @@
 #include <cstring>
 #include <errno.h>
 #include <iomanip>
 #include <signal.h>
 #include <sstream>
 #include <stdio.h>
 #include <sys/types.h>
 #include <windows.h>
-#include <Psapi.h>
+#include <psapi.h>
 
 namespace fuzzer {
 
 static const FuzzingOptions* HandlerOpt = nullptr;
 
 static LONG CALLBACK ExceptionHandler(PEXCEPTION_POINTERS ExceptionInfo) {
   switch (ExceptionInfo->ExceptionRecord->ExceptionCode) {
     case EXCEPTION_ACCESS_VIOLATION: