diff --git a/sensor_extension.c b/sensor_extension.c
index 63961b37..b506cb78 100644
--- a/sensor_extension.c
+++ b/sensor_extension.c
@@ -2,7 +2,8 @@
 // see example ...
 
 // put your library includes here
-
+#include <stdio.h>
+#include <string.h>
 
 // put your globals here