diff --git a/backend/pkg/db/clickhouse/connector.go b/backend/pkg/db/clickhouse/connector.go
index ea99288e7..c35f67fda 100644
--- a/backend/pkg/db/clickhouse/connector.go
+++ b/backend/pkg/db/clickhouse/connector.go
@@ -732,7 +732,7 @@ func (c *connectorImpl) InsertCustom(session *sessions.Session, msg *messages.Cu
 	if err != nil {
 		return fmt.Errorf("can't marshal custom event: %s", err)
 	}
-	var customPayload interface{}
+	customPayload := make(map[string]interface{})
 	if err := json.Unmarshal([]byte(msg.Payload), &customPayload); err != nil {
 		log.Printf("can't unmarshal custom event payload into object: %s", err)
 		customPayload = map[string]interface{}{