diff --git a/src/modules/module-client-node/client-node.c b/src/modules/module-client-node/client-node.c
index 37ab57222..a739916f0 100644
--- a/src/modules/module-client-node/client-node.c
+++ b/src/modules/module-client-node/client-node.c
@@ -615,11 +615,12 @@ static int do_port_set_io(struct impl *impl,
 		if ((mem = pw_memblock_find(data)) == NULL)
 			return -EINVAL;
 
-		mem_offset = mem->offset;
+		mem_offset = SPA_PTRDIFF(data, mem->ptr);
 		mem_size = mem->size;
 		if (mem_size - mem_offset < size)
 			return -EINVAL;
 
+		mem_offset += mem->offset;
 		m = ensure_mem(impl, mem->fd, t->data.MemFd, mem->flags);
 		memid = m->id;
 	}
@@ -1312,7 +1313,7 @@ static void node_port_added(void *data, struct pw_port *port)
 {
 	struct impl *impl = data;
 
-	pw_log_debug("client-node %p: port added", &impl->this);
+	pw_log_debug("client-node %p: port %p added", &impl->this, port);
 	port->mix_node.port_set_io = mix_port_set_io;
 	port->mix_node.process_input = mix_port_process_input;
 	port->mix_node.process_output = mix_port_process_output;