diff --git a/source/coap_security_handler.c b/source/coap_security_handler.c
index a45c357bcf..e239857111 100644
--- a/source/coap_security_handler.c
+++ b/source/coap_security_handler.c
@@ -8,6 +8,7 @@
 
 #include "mbedtls/sha256.h"
 #include "mbedtls/error.h"
+#include "mbedtls/platform.h"
 #include "mbedtls/ssl_cookie.h"
 #include "mbedtls/entropy_poll.h"
 #include "mbedtls/ssl.h"
diff --git a/source/include/coap_security_handler.h b/source/include/coap_security_handler.h
index bd6d6ba81e..e43c74bb7d 100644
--- a/source/include/coap_security_handler.h
+++ b/source/include/coap_security_handler.h
@@ -21,6 +21,7 @@
 #include <stddef.h>
 #include <inttypes.h>
 #include <stdbool.h>
+#include "mbedtls/platform.h"
 #include "mbedtls/ssl.h"
 #include "mbedtls/sha256.h"
 #include "mbedtls/entropy.h"