diff --git a/lib/Support/MSFileSystemBasic.cpp b/lib/Support/MSFileSystemBasic.cpp
index b8cbb4790..328182148 100644
--- a/lib/Support/MSFileSystemBasic.cpp
+++ b/lib/Support/MSFileSystemBasic.cpp
@@ -16,8 +16,8 @@
 
 #include "dxc/Support/WinIncludes.h"
 
-#include <D3Dcommon.h>
 #include <assert.h>
+#include <d3dcommon.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <io.h>
diff --git a/tools/clang/unittests/HLSL/MSFileSysTest.cpp b/tools/clang/unittests/HLSL/MSFileSysTest.cpp
index 570786528..42c86df30 100644
--- a/tools/clang/unittests/HLSL/MSFileSysTest.cpp
+++ b/tools/clang/unittests/HLSL/MSFileSysTest.cpp
@@ -18,7 +18,7 @@
 #include "llvm/Support/MSFileSystem.h"
 #include "llvm/Support/Atomic.h"
 
-#include <D3Dcommon.h>
+#include <d3dcommon.h>
 #include "dxc/dxcapi.internal.h"
 
 #include <algorithm>