diff --git a/spa/plugins/audioconvert/merger.c b/spa/plugins/audioconvert/merger.c
index 641d3d5bd..482f908ce 100644
--- a/spa/plugins/audioconvert/merger.c
+++ b/spa/plugins/audioconvert/merger.c
@@ -977,7 +977,11 @@ static int impl_node_process(void *object)
 	dd = &dbuf->buf->datas[0];
 
 	maxsize = dd->maxsize;
-	n_samples = maxsize / outport->stride;
+
+	if (SPA_LIKELY(this->io_position))
+		n_samples = this->io_position->clock.duration;
+	else
+		n_samples = maxsize / outport->stride;
 
 	src_datas = alloca(sizeof(void*) * this->port_count);