diff --git a/dlls/urlmon/urlmon_main.h b/dlls/urlmon/urlmon_main.h
index fd1327952ff..5de1afeebd4 100644
--- a/dlls/urlmon/urlmon_main.h
+++ b/dlls/urlmon/urlmon_main.h
@@ -232,24 +232,24 @@ void release_notif_hwnd(HWND) DECLSPEC_HIDDEN;
 
 const char *debugstr_bindstatus(ULONG) 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 void *heap_alloc_zero(size_t len)
+static inline void* __WINE_ALLOC_SIZE(1) heap_alloc_zero(size_t size)
 {
-    return HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, len);
+    return HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, size);
 }
 
-static inline void *heap_realloc(void *mem, size_t len)
+static inline void* __WINE_ALLOC_SIZE(2) heap_realloc(void *mem, size_t size)
 {
-    return HeapReAlloc(GetProcessHeap(), 0, mem, len);
+    return HeapReAlloc(GetProcessHeap(), 0, mem, size);
 }
 
-static inline void *heap_realloc_zero(void *mem, size_t len)
+static inline void* __WINE_ALLOC_SIZE(2) heap_realloc_zero(void *mem, size_t size)
 {
-    return HeapReAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, mem, len);
+    return HeapReAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, mem, size);
 }
 
 static inline BOOL heap_free(void *mem)