diff --git a/libraries/AP_Common/AP_Common.h b/libraries/AP_Common/AP_Common.h
index 2d9639f27a..30faec3039 100644
--- a/libraries/AP_Common/AP_Common.h
+++ b/libraries/AP_Common/AP_Common.h
@@ -16,6 +16,7 @@
 #define __AP_COMMON_H__
 
 #include <stdint.h>
+#include <stdlib.h>
 #include <stdbool.h>
 
 #pragma GCC diagnostic warning "-Wall"