diff --git a/loader/win32.c b/loader/win32.c
index 1633b26dd2..7dd10fe237 100644
--- a/loader/win32.c
+++ b/loader/win32.c
@@ -2689,7 +2689,7 @@ static void WINAPI expCoTaskMemFree(void* cb)
 
 
 
-void* CoTaskMemAlloc(ULONG cb)
+void* CoTaskMemAlloc(unsigned long cb)
 {
     return expCoTaskMemAlloc(cb);
 }