diff --git a/reactos/win32ss/user/ntuser/callback.c b/reactos/win32ss/user/ntuser/callback.c
index 6bd8060c9d3..a9d6939d2c0 100644
--- a/reactos/win32ss/user/ntuser/callback.c
+++ b/reactos/win32ss/user/ntuser/callback.c
@@ -296,6 +296,9 @@ co_IntCallWindowProc(WNDPROC Proc,
    ULONG ArgumentLength;
    LRESULT Result;
 
+   TRACE("co_IntCallWindowProc(Proc %p, IsAnsiProc: %s, Wnd %p, Message %u, wParam %Iu, lParam %Id, lParamBufferSize %d)\n",
+       Proc, IsAnsiProc ? "TRUE" : "FALSE", Wnd, Message, wParam, lParam, lParamBufferSize);
+
    /* Do not allow the desktop thread to do callback to user mode */
    ASSERT(PsGetCurrentThreadWin32Thread() != gptiDesktopThread);