diff --git a/dlls/wimgapi/main.c b/dlls/wimgapi/main.c
index 5ac8a66120c..d7c3babb444 100644
--- a/dlls/wimgapi/main.c
+++ b/dlls/wimgapi/main.c
@@ -44,3 +44,9 @@ BOOL WINAPI DllMain(HINSTANCE instance, DWORD reason, void *reserved)
 
     return TRUE;
 }
+
+DWORD WINAPI WIMRegisterMessageCallback(HANDLE wim, FARPROC callback, PVOID data)
+{
+    FIXME("(%p %p %p) stub\n", wim, callback, data);
+    return 0;
+}
diff --git a/dlls/wimgapi/wimgapi.spec b/dlls/wimgapi/wimgapi.spec
index b4679898ee4..7464a5a1553 100644
--- a/dlls/wimgapi/wimgapi.spec
+++ b/dlls/wimgapi/wimgapi.spec
@@ -28,7 +28,7 @@
 @ stub WIMMountImageHandle
 @ stub WIMReadImageFile
 @ stub WIMRegisterLogFile
-@ stub WIMRegisterMessageCallback
+@ stdcall WIMRegisterMessageCallback(long ptr ptr)
 @ stub WIMRemountImage
 @ stub WIMSetBootImage
 @ stub WIMSetFileIOCallbackTemporaryPath