diff --git a/include/osmocom/iuh/hnbgw.h b/include/osmocom/iuh/hnbgw.h
index db49dc15..4e02d5f8 100644
--- a/include/osmocom/iuh/hnbgw.h
+++ b/include/osmocom/iuh/hnbgw.h
@@ -101,6 +101,10 @@ struct hnb_context {
 	 * this entire data structure is freed if the HNB sends HNB-DE-REGISTER-REQ. */
 	bool hnb_registered;
 
+	/*! True if a HNB-REGISTER-REJECT has been sent to this HNB. If this flag
+	 * is set we will close the connection once its Tx queue has been flushed. */
+	bool hnb_rejected;
+
 	/* linked list of hnbgw_context_map */
 	struct llist_head map_list;
 };
diff --git a/src/hnbgw.c b/src/hnbgw.c
index cd492bb2..188b292c 100644
--- a/src/hnbgw.c
+++ b/src/hnbgw.c
@@ -267,6 +267,15 @@ out:
 	return rc;
 }
 
+static void txflushed_cb(struct osmo_stream_srv *conn, void *data)
+{
+	struct hnb_context *hnb = osmo_stream_srv_get_data(conn);
+
+	/* Close connection after sending HNB-REGISTER-REJECT and the Tx queue has been flushed. */
+	if (hnb->hnb_rejected)
+		hnb_context_release(hnb);
+}
+
 struct hnb_context *hnb_context_alloc(struct hnb_gw *gw, struct osmo_stream_srv_link *link, int new_fd)
 {
 	struct hnb_context *ctx;
@@ -284,6 +293,8 @@ struct hnb_context *hnb_context_alloc(struct hnb_gw *gw, struct osmo_stream_srv_
 		return NULL;
 	}
 
+	osmo_stream_srv_set_txflushed_cb(ctx->conn, txflushed_cb);
+
 	llist_add_tail(&ctx->list, &gw->hnb_list);
 	return ctx;
 }
diff --git a/src/hnbgw_hnbap.c b/src/hnbgw_hnbap.c
index c9a8807e..207f49ff 100644
--- a/src/hnbgw_hnbap.c
+++ b/src/hnbgw_hnbap.c
@@ -428,7 +428,15 @@ static int hnbgw_rx_hnb_register_req(struct hnb_context *ctx, ANY_t *in)
 			     "MCC=%u,MNC=%u,LAC=%u,RAC=%u,SAC=%u,CID=%u from %s\n",
 			     ctx->id.mcc, ctx->id.mnc, ctx->id.lac, ctx->id.rac, ctx->id.sac, ctx->id.cid, name);
 			talloc_free(name);
-			return hnbgw_tx_hnb_register_rej(ctx);
+			rc = hnbgw_tx_hnb_register_rej(ctx);
+			if (rc != 0) {
+				/* The message was not queued. Clean up HNB right away. */
+				hnb_context_release(ctx);
+			} else {
+				/* Release the HNB once the message has been sent. */
+				ctx->hnb_rejected = true;
+			}
+			return rc;
 		}
 	}