diff --git a/include/lib/libc/aarch64/stddef_.h b/include/lib/libc/aarch64/stddef_.h
index b7d8209..6ecc606 100644
--- a/include/lib/libc/aarch64/stddef_.h
+++ b/include/lib/libc/aarch64/stddef_.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2018-2019, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -12,9 +12,4 @@
 #define SIZET_
 #endif
 
-#ifndef _PTRDIFF_T
-typedef long ptrdiff_t;
-#define _PTRDIFF_T
-#endif
-
 #endif /* STDDEF__H */