diff --git a/reactos/tools/wmc/windows.h b/reactos/tools/wmc/windows.h
index 1f3e094651d..48d43b76245 100644
--- a/reactos/tools/wmc/windows.h
+++ b/reactos/tools/wmc/windows.h
@@ -1,3 +1,31 @@
 #include <wchar.h>
 typedef wchar_t WCHAR;
 typedef unsigned short int WORD;
+typedef unsigned int UINT;
+typedef unsigned int DWORD;
+typedef char CHAR;
+typedef CHAR *LPSTR;
+typedef WCHAR *LPWSTR;
+typedef const CHAR *LPCSTR;
+typedef const WCHAR *LPCWSTR;
+typedef unsigned int *LPBOOL;
+
+#define STDCALL __attribute__((stdcall))
+
+int STDCALL MultiByteToWideChar(
+  UINT CodePage,
+  DWORD dwFlags,
+  LPCSTR lpMultiByteStr,
+  int cbMultiByte,
+  LPWSTR lpWideCharStr,
+  int cchWideChar);
+
+int STDCALL WideCharToMultiByte(
+  UINT CodePage,
+  DWORD dwFlags,
+  LPCWSTR lpWideCharStr,
+  int cchWideChar,
+  LPSTR lpMultiByteStr,
+  int cbMultiByte,
+  LPCSTR lpDefaultChar,
+  LPBOOL lpUsedDefaultChar);