diff --git a/include/lib/cassert.h b/include/lib/cassert.h
index 40cb483..3119e1f 100644
--- a/include/lib/cassert.h
+++ b/include/lib/cassert.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2014-2018, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -7,6 +7,8 @@
 #ifndef __CASSERT_H__
 #define __CASSERT_H__
 
+#include <cdefs.h>
+
 /*******************************************************************************
  * Macro to flag a compile time assertion. It uses the preprocessor to generate
  * an invalid C construct if 'cond' evaluates to false.