diff --git a/subsys/bluetooth/controller/ll_sw/Makefile b/subsys/bluetooth/controller/ll_sw/Makefile
index c60465a75cc..00f29c77488 100644
--- a/subsys/bluetooth/controller/ll_sw/Makefile
+++ b/subsys/bluetooth/controller/ll_sw/Makefile
@@ -2,3 +2,4 @@ ccflags-$(CONFIG_BLUETOOTH_LL_SW) += -I$(srctree)/subsys/bluetooth/controller/in
 ccflags-$(CONFIG_BLUETOOTH_LL_SW) += -I$(srctree)/subsys/bluetooth/controller
 obj-$(CONFIG_BLUETOOTH_LL_SW) += ctrl.o
 obj-$(CONFIG_BLUETOOTH_LL_SW) += ll.o
+obj-$(CONFIG_BLUETOOTH_LL_SW) += crypto.o
diff --git a/subsys/bluetooth/controller/ll_sw/crypto.c b/subsys/bluetooth/controller/ll_sw/crypto.c
new file mode 100644
index 00000000000..3fdb1617c21
--- /dev/null
+++ b/subsys/bluetooth/controller/ll_sw/crypto.c
@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) 2016-2017 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#include <soc.h>
+#include "hal/cpu.h"
+#include "hal/rand.h"
+
+K_MUTEX_DEFINE(mutex_rand);
+
+int bt_rand(void *buf, size_t len)
+{
+	while (len) {
+		k_mutex_lock(&mutex_rand, K_FOREVER);
+		len = rand_get(len, buf);
+		k_mutex_unlock(&mutex_rand);
+		if (len) {
+			cpu_sleep();
+		}
+	}
+
+	return 0;
+}
diff --git a/subsys/bluetooth/controller/ll_sw/ll.c b/subsys/bluetooth/controller/ll_sw/ll.c
index 9deacc891b0..df304a193cc 100644
--- a/subsys/bluetooth/controller/ll_sw/ll.c
+++ b/subsys/bluetooth/controller/ll_sw/ll.c
@@ -46,8 +46,6 @@ static uint8_t MALIGN(4) _ticker_user_ops[RADIO_TICKER_USER_OPS]
 						[TICKER_USER_OP_T_SIZE];
 static uint8_t MALIGN(4) _radio[LL_MEM_TOTAL];
 
-K_MUTEX_DEFINE(mutex_rand);
-
 static struct k_sem *sem_recv;
 
 static struct {
@@ -74,20 +72,6 @@ static struct {
 	uint8_t filter_policy:1;
 } _ll_scan_params;
 
-int bt_rand(void *buf, size_t len)
-{
-	while (len) {
-		k_mutex_lock(&mutex_rand, K_FOREVER);
-		len = rand_get(len, buf);
-		k_mutex_unlock(&mutex_rand);
-		if (len) {
-			cpu_sleep();
-		}
-	}
-
-	return 0;
-}
-
 void mayfly_enable_cb(uint8_t caller_id, uint8_t callee_id, uint8_t enable)
 {
 	(void)caller_id;