diff --git a/dlls/api-ms-win-downlevel-kernel32-l2-1-0/api-ms-win-downlevel-kernel32-l2-1-0.spec b/dlls/api-ms-win-downlevel-kernel32-l2-1-0/api-ms-win-downlevel-kernel32-l2-1-0.spec
index c007021e3e3..750badec24b 100644
--- a/dlls/api-ms-win-downlevel-kernel32-l2-1-0/api-ms-win-downlevel-kernel32-l2-1-0.spec
+++ b/dlls/api-ms-win-downlevel-kernel32-l2-1-0/api-ms-win-downlevel-kernel32-l2-1-0.spec
@@ -94,7 +94,7 @@
 @ stdcall RegisterWaitForSingleObject(ptr long ptr ptr long long) kernel32.RegisterWaitForSingleObject
 @ stdcall SetConsoleTitleA(str) kernel32.SetConsoleTitleA
 @ stdcall SetFileCompletionNotificationModes(long long) kernel32.SetFileCompletionNotificationModes
-@ stub SetFirmwareEnvironmentVariableW
+@ stdcall SetFirmwareEnvironmentVariableW(wstr wstr ptr long) kernel32.SetFirmwareEnvironmentVariableW
 @ stdcall SetHandleCount(long) kernel32.SetHandleCount
 @ stdcall SetMailslotInfo(long long) kernel32.SetMailslotInfo
 @ stdcall SetProcessAffinityMask(long long) kernel32.SetProcessAffinityMask
diff --git a/dlls/kernel32/kernel32.spec b/dlls/kernel32/kernel32.spec
index 0c64144d7fa..7b89d19c2d3 100644
--- a/dlls/kernel32/kernel32.spec
+++ b/dlls/kernel32/kernel32.spec
@@ -1414,7 +1414,7 @@
 @ stdcall -import SetFileTime(long ptr ptr ptr)
 @ stdcall -import SetFileValidData(ptr int64)
 # @ stub SetFirmwareEnvironmentVariableA
-# @ stub SetFirmwareEnvironmentVariableW
+@ stdcall SetFirmwareEnvironmentVariableW(wstr wstr ptr long)
 @ stdcall SetHandleContext(long long)
 @ stdcall SetHandleCount(long)
 @ stdcall -import SetHandleInformation(long long long)
diff --git a/dlls/kernel32/process.c b/dlls/kernel32/process.c
index cfc11c867ae..b2bd5980fd9 100644
--- a/dlls/kernel32/process.c
+++ b/dlls/kernel32/process.c
@@ -770,6 +770,16 @@ DWORD WINAPI GetFirmwareEnvironmentVariableW(LPCWSTR name, LPCWSTR guid, PVOID b
     return 0;
 }
 
+/***********************************************************************
+ *           SetFirmwareEnvironmentVariableW     (KERNEL32.@)
+ */
+BOOL WINAPI SetFirmwareEnvironmentVariableW(const WCHAR *name, const WCHAR *guid, void *buffer, DWORD size)
+{
+    FIXME("stub: %s %s %p %u\n", debugstr_w(name), debugstr_w(guid), buffer, size);
+    SetLastError(ERROR_INVALID_FUNCTION);
+    return FALSE;
+}
+
 /**********************************************************************
  *           GetNumaNodeProcessorMask     (KERNEL32.@)
  */