diff --git a/include/common/buf.h b/include/common/buf.h
index 02a66b366..6eec42292 100644
--- a/include/common/buf.h
+++ b/include/common/buf.h
@@ -396,10 +396,6 @@ static inline void b_set_data(struct buffer *b, size_t len)
  */
 static inline void b_del(struct buffer *b, size_t del)
 {
-	if (del >= b->output)
-		b->output = 0;
-	else
-		b->output -= del;
 	b->len  -= del;
 	b->head += del;
 	if (b->head >= b->size)
diff --git a/include/proto/channel.h b/include/proto/channel.h
index 291bb08f8..624123799 100644
--- a/include/proto/channel.h
+++ b/include/proto/channel.h
@@ -767,6 +767,7 @@ static inline void channel_slow_realign(struct channel *chn, char *swap)
 static inline void co_skip(struct channel *chn, int len)
 {
 	b_del(chn->buf, len);
+	chn->buf->output -= len;
 	c_realign_if_empty(chn);
 
 	/* notify that some data was written to the SI from the buffer */