diff --git a/src/MQTTProtocolClient.c b/src/MQTTProtocolClient.c
index 6380eb31..406fe392 100644
--- a/src/MQTTProtocolClient.c
+++ b/src/MQTTProtocolClient.c
@@ -30,6 +30,7 @@
 
 #include <stdlib.h>
 #include <string.h>
+#include <stdint.h>
 
 #include "MQTTProtocolClient.h"
 #if !defined(NO_PERSISTENCE)