diff --git a/apps/openmw/main.cpp b/apps/openmw/main.cpp
index 070136dfd..2d2c9af0c 100644
--- a/apps/openmw/main.cpp
+++ b/apps/openmw/main.cpp
@@ -15,7 +15,7 @@
 #if defined(_WIN32)
 // For OutputDebugString
 #define WIN32_LEAN_AND_MEAN
-#include <Windows.h>
+#include <windows.h>
 // makes __argc and __argv available on windows
 #include <cstdlib>
 #endif
diff --git a/extern/oics/tinyxml.cpp b/extern/oics/tinyxml.cpp
index 21b2d9c9a..5d8eb475a 100644
--- a/extern/oics/tinyxml.cpp
+++ b/extern/oics/tinyxml.cpp
@@ -32,7 +32,7 @@ distribution.
 #include "tinyxml.h"
 
 #ifdef _WIN32
-#include <Windows.h> // import MultiByteToWideChar
+#include <windows.h> // import MultiByteToWideChar
 #endif