diff --git a/tests/bluetooth/bsim_bt/bsim_test_gatt_caching/src/common.c b/tests/bluetooth/bsim_bt/bsim_test_gatt_caching/src/common.c
index 5b5f463d6c2..a7083921905 100644
--- a/tests/bluetooth/bsim_bt/bsim_test_gatt_caching/src/common.c
+++ b/tests/bluetooth/bsim_bt/bsim_test_gatt_caching/src/common.c
@@ -21,6 +21,7 @@ void test_init(void)
 }
 
 #define CHANNEL_ID 0
+#define MSG_SIZE 1
 
 void backchannel_init(void)
 {
@@ -39,8 +40,7 @@ void backchannel_init(void)
 
 void backchannel_sync_send(void)
 {
-	/* Dummy message */
-	uint8_t sync_msg[] = { 'A' };
+	uint8_t sync_msg[MSG_SIZE] = { get_device_nbr() };
 
 	printk("Sending sync\n");
 	bs_bc_send_msg(CHANNEL_ID, sync_msg, ARRAY_SIZE(sync_msg));
@@ -48,7 +48,17 @@ void backchannel_sync_send(void)
 
 void backchannel_sync_wait(void)
 {
-	while (!bs_bc_is_msg_received(CHANNEL_ID)) {
+	uint8_t sync_msg[MSG_SIZE];
+
+	while (true) {
+		if (bs_bc_is_msg_received(CHANNEL_ID) > 0) {
+			bs_bc_receive_msg(CHANNEL_ID, sync_msg, ARRAY_SIZE(sync_msg));
+			if (sync_msg[0] != get_device_nbr()) {
+				/* Received a message from another device, exit */
+				break;
+			}
+		}
+
 		k_sleep(K_MSEC(1));
 	}