diff --git a/dlls/user/message.c b/dlls/user/message.c
index c92db6a5c20..d2af2bd3567 100644
--- a/dlls/user/message.c
+++ b/dlls/user/message.c
@@ -3356,7 +3356,7 @@ UINT_PTR WINAPI SetTimer( HWND hwnd, UINT_PTR id, UINT timeout, TIMERPROC proc )
         req->msg    = WM_TIMER;
         req->id     = id;
         req->rate   = max( timeout, SYS_TIMER_RATE );
-        req->lparam = (unsigned int)winproc;
+        req->lparam = (unsigned long)winproc;
         if (!wine_server_call_err( req ))
         {
             ret = reply->id;
@@ -3387,7 +3387,7 @@ UINT_PTR WINAPI SetSystemTimer( HWND hwnd, UINT_PTR id, UINT timeout, TIMERPROC
         req->msg    = WM_SYSTIMER;
         req->id     = id;
         req->rate   = max( timeout, SYS_TIMER_RATE );
-        req->lparam = (unsigned int)winproc;
+        req->lparam = (unsigned long)winproc;
         if (!wine_server_call_err( req ))
         {
             ret = reply->id;