diff --git a/sdk/lib/ucrt/locale/MultiByteToWideChar.c b/sdk/lib/ucrt/locale/MultiByteToWideChar.c
new file mode 100644
index 00000000000..fab0e2656a9
--- /dev/null
+++ b/sdk/lib/ucrt/locale/MultiByteToWideChar.c
@@ -0,0 +1,31 @@
+//
+// MultiByteToWideChar.c
+//
+//      Copyright (c) 2024 Timo Kreuzer
+//
+// Definition of __acrt_MultiByteToWideChar.
+//
+// SPDX-License-Identifier: MIT
+//
+
+#include <windows.h>
+//#include <stringapiset.h>
+
+_Success_(return != 0)
+int
+__cdecl
+__acrt_MultiByteToWideChar (
+    _In_ UINT _CodePage,
+    _In_ DWORD _DWFlags,
+    _In_ LPCSTR _LpMultiByteStr,
+    _In_ int _CbMultiByte,
+    _Out_writes_opt_(_CchWideChar) LPWSTR _LpWideCharStr,
+    _In_ int _CchWideChar)
+{
+    return MultiByteToWideChar(_CodePage,
+                               _DWFlags,
+                               _LpMultiByteStr,
+                               _CbMultiByte,
+                               _LpWideCharStr,
+                               _CchWideChar);
+}
diff --git a/sdk/lib/ucrt/locale/locale.cmake b/sdk/lib/ucrt/locale/locale.cmake
index 038a0f46dc0..7227d7e8d1f 100644
--- a/sdk/lib/ucrt/locale/locale.cmake
+++ b/sdk/lib/ucrt/locale/locale.cmake
@@ -20,6 +20,7 @@ list(APPEND UCRT_LOCALE_SOURCES
     locale/localeconv.cpp
     locale/locale_refcounting.cpp
     locale/locale_update.cpp
+    locale/MultiByteToWideChar.c
     locale/nlsdata.cpp
     locale/setlocale.cpp
     locale/wsetlocale.cpp