diff --git a/include/mbedtls/aes.h b/include/mbedtls/aes.h
index ab8793c..a74e413 100644
--- a/include/mbedtls/aes.h
+++ b/include/mbedtls/aes.h
@@ -45,6 +45,7 @@
 #else
 #include MBEDTLS_CONFIG_FILE
 #endif
+#include "mbedtls/platform_util.h"
 
 #include <stddef.h>
 #include <stdint.h>