diff --git a/src/le-audio/gatt-service/broadcast_audio_scan_service_client.c b/src/le-audio/gatt-service/broadcast_audio_scan_service_client.c
index 0fe2b615e..3518ee46d 100644
--- a/src/le-audio/gatt-service/broadcast_audio_scan_service_client.c
+++ b/src/le-audio/gatt-service/broadcast_audio_scan_service_client.c
@@ -121,6 +121,8 @@ static void bass_client_reset_source(bass_client_source_t * source){
 }
 
 static void bass_client_emit_connection_established(bass_client_connection_t * connection, uint8_t status){
+    btstack_assert(bass_event_callback != NULL);
+
     uint8_t event[8];
     uint16_t pos = 0;
     event[pos++] = HCI_EVENT_GATTSERVICE_META;
@@ -135,6 +137,7 @@ static void bass_client_emit_connection_established(bass_client_connection_t * c
 }
 
 static void bass_client_emit_scan_operation_complete(bass_client_connection_t * connection, uint8_t status, bass_opcode_t opcode){
+    btstack_assert(bass_event_callback != NULL);
     uint8_t event[7];
     uint16_t pos = 0;
     event[pos++] = HCI_EVENT_GATTSERVICE_META;
@@ -148,6 +151,7 @@ static void bass_client_emit_scan_operation_complete(bass_client_connection_t *
 }
 
 static void bass_client_emit_source_operation_complete(bass_client_connection_t * connection, uint8_t status, bass_opcode_t opcode, uint8_t source_id){
+    btstack_assert(bass_event_callback != NULL);
     uint8_t event[8];
     uint16_t pos = 0;
     event[pos++] = HCI_EVENT_GATTSERVICE_META;
@@ -162,6 +166,7 @@ static void bass_client_emit_source_operation_complete(bass_client_connection_t
 }
 
 static void bass_client_emit_receive_state(bass_client_connection_t * connection, uint8_t source_id){
+    btstack_assert(bass_event_callback != NULL);
     uint8_t pos = 0;
     uint8_t event[7];
     event[pos++] = HCI_EVENT_GATTSERVICE_META;