diff --git a/dll/win32/msafd/misc/dllmain.c b/dll/win32/msafd/misc/dllmain.c
index 45a1d17df15..c2ee828b085 100644
--- a/dll/win32/msafd/misc/dllmain.c
+++ b/dll/win32/msafd/misc/dllmain.c
@@ -3524,7 +3524,7 @@ BOOLEAN SockCreateOrReferenceAsyncThread(VOID)
     /* Create the Async Thread */
     hAsyncThread = CreateThread(NULL,
                                 0,
-                                (LPTHREAD_START_ROUTINE)SockAsyncThread,
+                                SockAsyncThread,
                                 NULL,
                                 0,
                                 &AsyncThreadId);
@@ -3537,7 +3537,9 @@ BOOLEAN SockCreateOrReferenceAsyncThread(VOID)
     return TRUE;
 }
 
-int SockAsyncThread(PVOID ThreadParam)
+ULONG
+NTAPI
+SockAsyncThread(PVOID ThreadParam)
 {
     PVOID AsyncContext;
     PASYNC_COMPLETION_ROUTINE AsyncCompletionRoutine;
diff --git a/dll/win32/msafd/msafd.h b/dll/win32/msafd/msafd.h
index fa3396ed004..1b8d3cf4637 100644
--- a/dll/win32/msafd/msafd.h
+++ b/dll/win32/msafd/msafd.h
@@ -454,7 +454,9 @@ int CreateContext(
 	PSOCKET_INFORMATION Socket
 );
 
-int SockAsyncThread(
+ULONG
+NTAPI
+SockAsyncThread(
 	PVOID ThreadParam
 );