diff --git a/src/pipe.c b/src/pipe.c
index f3196545b..600828c50 100644
--- a/src/pipe.c
+++ b/src/pipe.c
@@ -107,6 +107,7 @@ static void usage()
 
 static void * send_loop(void *ctx)
 {
+	unsigned last_sequenceno = 0;
 	int ret, scanned, sent, ready, cnt = 0;
 	struct sample *smps[node->vectorize];
 
@@ -130,6 +131,14 @@ static void * send_loop(void *ctx)
 		else if (scanned == 0)
 			continue;
 
+		/* Fill in missing sequence numbers */
+		for (int i = 0; i < scanned; i++) {
+			if (smps[i]->flags & SAMPLE_HAS_SEQUENCE)
+				last_sequenceno = smps[i]->sequence;
+			else
+				smps[i]->sequence = last_sequenceno++;
+		}
+
 		sent = node_write(node, smps, scanned);
 		if (sent < 0) {
 			warn("Failed to sent samples to node %s: reason=%d", node_name(node), sent);