diff --git a/dlls/explorerframe/explorerframe_main.h b/dlls/explorerframe/explorerframe_main.h
index e6cea6375a6..ec8b3634c42 100644
--- a/dlls/explorerframe/explorerframe_main.h
+++ b/dlls/explorerframe/explorerframe_main.h
@@ -34,9 +34,9 @@ static inline void EFRAME_UnlockModule(void) { InterlockedDecrement( &EFRAME_ref
 HRESULT NamespaceTreeControl_Constructor(IUnknown *pUnkOuter, REFIID riid, void **ppv) DECLSPEC_HIDDEN;
 HRESULT TaskbarList_Constructor(IUnknown*,REFIID,void**) DECLSPEC_HIDDEN;
 
-static inline void *heap_alloc(size_t len)
+static inline void* __WINE_ALLOC_SIZE(1) heap_alloc(size_t size)
 {
-    return HeapAlloc(GetProcessHeap(), 0, len);
+    return HeapAlloc(GetProcessHeap(), 0, size);
 }
 
 static inline BOOL heap_free(void *mem)