diff --git a/nimble/controller/src/ble_ll_adv.c b/nimble/controller/src/ble_ll_adv.c
index 3fa0c7706..4654cb267 100644
--- a/nimble/controller/src/ble_ll_adv.c
+++ b/nimble/controller/src/ble_ll_adv.c
@@ -17,6 +17,7 @@
  * under the License.
  */
 #include <stdint.h>
+#include <stdlib.h>
 #include <string.h>
 #include <assert.h>
 #include "syscfg/syscfg.h"