diff --git a/tests/bsim/bluetooth/host/gatt/authorization/src/gatt_client_test.c b/tests/bsim/bluetooth/host/gatt/authorization/src/gatt_client_test.c
index 9c60c5b57b2..d276bfcedc3 100644
--- a/tests/bsim/bluetooth/host/gatt/authorization/src/gatt_client_test.c
+++ b/tests/bsim/bluetooth/host/gatt/authorization/src/gatt_client_test.c
@@ -60,7 +60,7 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 	UNSET_FLAG(flag_is_connected);
 }
 
-BT_CONN_CB_DEFINE(conn_callbacks) = {
+static struct bt_conn_cb conn_callbacks = {
 	.connected = connected,
 	.disconnected = disconnected,
 };
@@ -297,6 +297,8 @@ static void test_main(void)
 {
 	int err;
 
+	bt_conn_cb_register(&conn_callbacks);
+
 	err = bt_enable(NULL);
 	if (err != 0) {
 		FAIL("Bluetooth discover failed (err %d)\n", err);
diff --git a/tests/bsim/bluetooth/host/gatt/authorization/src/gatt_server_test.c b/tests/bsim/bluetooth/host/gatt/authorization/src/gatt_server_test.c
index 03942821640..a09b94367fb 100644
--- a/tests/bsim/bluetooth/host/gatt/authorization/src/gatt_server_test.c
+++ b/tests/bsim/bluetooth/host/gatt/authorization/src/gatt_server_test.c
@@ -45,7 +45,7 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 	g_conn = NULL;
 }
 
-BT_CONN_CB_DEFINE(conn_callbacks) = {
+static struct bt_conn_cb conn_callbacks = {
 	.connected = connected,
 	.disconnected = disconnected,
 };
@@ -331,6 +331,8 @@ static void test_main(void)
 		return;
 	}
 
+	bt_conn_cb_register(&conn_callbacks);
+
 	err = bt_enable(NULL);
 	if (err != 0) {
 		FAIL("Bluetooth init failed (err %d)\n", err);
diff --git a/tests/bsim/bluetooth/host/gatt/general/src/gatt_client_test.c b/tests/bsim/bluetooth/host/gatt/general/src/gatt_client_test.c
index 0ae87791f81..cc233510b0b 100644
--- a/tests/bsim/bluetooth/host/gatt/general/src/gatt_client_test.c
+++ b/tests/bsim/bluetooth/host/gatt/general/src/gatt_client_test.c
@@ -74,7 +74,7 @@ static void security_changed(struct bt_conn *conn, bt_security_t level, enum bt_
 	}
 }
 
-BT_CONN_CB_DEFINE(conn_callbacks) = {
+static struct bt_conn_cb conn_callbacks = {
 	.connected = connected,
 	.disconnected = disconnected,
 	.security_changed = security_changed,
@@ -351,6 +351,8 @@ static void test_main(void)
 {
 	int err;
 
+	bt_conn_cb_register(&conn_callbacks);
+
 	err = bt_enable(NULL);
 	if (err != 0) {
 		FAIL("Bluetooth discover failed (err %d)\n", err);
diff --git a/tests/bsim/bluetooth/host/gatt/general/src/gatt_server_test.c b/tests/bsim/bluetooth/host/gatt/general/src/gatt_server_test.c
index e41d568dff8..c77fe39c000 100644
--- a/tests/bsim/bluetooth/host/gatt/general/src/gatt_server_test.c
+++ b/tests/bsim/bluetooth/host/gatt/general/src/gatt_server_test.c
@@ -47,7 +47,7 @@ static void disconnected(struct bt_conn *conn, uint8_t reason)
 	UNSET_FLAG(flag_is_connected);
 }
 
-BT_CONN_CB_DEFINE(conn_callbacks) = {
+static struct bt_conn_cb conn_callbacks = {
 	.connected = connected,
 	.disconnected = disconnected,
 };
@@ -151,6 +151,8 @@ static void test_main(void)
 		BT_DATA_BYTES(BT_DATA_FLAGS, (BT_LE_AD_GENERAL | BT_LE_AD_NO_BREDR))
 	};
 
+	bt_conn_cb_register(&conn_callbacks);
+
 	err = bt_enable(NULL);
 	if (err != 0) {
 		FAIL("Bluetooth init failed (err %d)\n", err);