diff --git a/cpu/cc26xx-cc13xx/dev/aux-ctrl.c b/cpu/cc26xx-cc13xx/dev/aux-ctrl.c
index eb316d3df..48d2da460 100644
--- a/cpu/cc26xx-cc13xx/dev/aux-ctrl.c
+++ b/cpu/cc26xx-cc13xx/dev/aux-ctrl.c
@@ -36,6 +36,7 @@
 
 #include <stdint.h>
 #include <stdbool.h>
+#include <stddef.h>
 /*---------------------------------------------------------------------------*/
 LIST(consumers_list);
 /*---------------------------------------------------------------------------*/