diff --git a/drivers/include/periph/flashpage.h b/drivers/include/periph/flashpage.h
index 9080e3336c..737cca601d 100644
--- a/drivers/include/periph/flashpage.h
+++ b/drivers/include/periph/flashpage.h
@@ -48,6 +48,7 @@
 #ifndef PERIPH_FLASHPAGE_H
 #define PERIPH_FLASHPAGE_H
 
+#include <stddef.h>
 #include <stdint.h>
 
 #include "cpu_conf.h"