diff --git a/kernel/relay.c b/kernel/relay.c
index 4311101..e61156e 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -899,7 +899,10 @@
 	size_t read_subbuf, padding, padding_start, padding_end;
 	size_t subbuf_size = buf->chan->subbuf_size;
 	size_t n_subbufs = buf->chan->n_subbufs;
+	size_t consumed = buf->subbufs_consumed % n_subbufs;
 
+	if (!read_pos)
+		read_pos = consumed * subbuf_size + buf->bytes_consumed;
 	read_subbuf = read_pos / subbuf_size;
 	padding = buf->padding[read_subbuf];
 	padding_start = (read_subbuf + 1) * subbuf_size - padding;