diff --git a/dlls/ntdll/signal_i386.c b/dlls/ntdll/signal_i386.c
index 05ede349978..0344a2968d7 100644
--- a/dlls/ntdll/signal_i386.c
+++ b/dlls/ntdll/signal_i386.c
@@ -1569,7 +1569,7 @@ static BOOL check_atl_thunk( EXCEPTION_RECORD *rec, CONTEXT *context )
     const struct atl_thunk *thunk = (const struct atl_thunk *)rec->ExceptionInformation[1];
     BOOL ret = FALSE;
 
-    if (!virtual_is_valid_code_address( thunk, sizeof(thunk) )) return FALSE;
+    if (!virtual_is_valid_code_address( thunk, sizeof(*thunk) )) return FALSE;
 
     __TRY
     {