diff --git a/include/common/buffer.h b/include/common/buffer.h
index 44b188384..e0b6c962f 100644
--- a/include/common/buffer.h
+++ b/include/common/buffer.h
@@ -61,16 +61,10 @@ void buffer_dump(FILE *o, struct buffer *b, int from, int to);
 
 /***** FIXME: OLD API BELOW *****/
 
-/* Return non-zero only if the buffer is not empty */
-static inline int buffer_not_empty(const struct buffer *buf)
-{
-	return buf->i | buf->o;
-}
-
 /* Return non-zero only if the buffer is empty */
 static inline int buffer_empty(const struct buffer *buf)
 {
-	return !buffer_not_empty(buf);
+	return !b_data(buf);
 }
 
 /* Returns non-zero if the buffer's INPUT is considered full, which means that
diff --git a/src/buffer.c b/src/buffer.c
index d6320c685..416cb4c2c 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -89,7 +89,7 @@ int buffer_replace2(struct buffer *b, char *pos, char *end, const char *str, int
 	if (b_tail(b) + delta > b->data + b->size)
 		return 0;  /* no space left */
 
-	if (buffer_not_empty(b) &&
+	if (b_data(b) &&
 	    b_tail(b) + delta > b_head(b) &&
 	    b_head(b) >= b_tail(b))
 		return 0;  /* no space left before wrapping data */
@@ -128,7 +128,7 @@ int buffer_insert_line2(struct buffer *b, char *pos, const char *str, int len)
 	if (b_tail(b) + delta >= b->data + b->size)
 		return 0;  /* no space left */
 
-	if (buffer_not_empty(b) &&
+	if (b_data(b) &&
 	    b_tail(b) + delta > b_head(b) &&
 	    b_head(b) >= b_tail(b))
 		return 0;  /* no space left before wrapping data */
diff --git a/src/proto_http.c b/src/proto_http.c
index 78e0badd5..3d83e1b4b 100644
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -1631,7 +1631,7 @@ int http_wait_for_request(struct stream *s, struct channel *req, int an_bit)
 	s->srv_error = http_return_srv_error;
 
 	/* If there is data available for analysis, log the end of the idle time. */
-	if (buffer_not_empty(req->buf) && s->logs.t_idle == -1)
+	if (c_data(req) && s->logs.t_idle == -1)
 		s->logs.t_idle = tv_ms_elapsed(&s->logs.tv_accept, &now) - s->logs.t_handshake;
 
 	/* There's a protected area at the end of the buffer for rewriting
@@ -1639,7 +1639,7 @@ int http_wait_for_request(struct stream *s, struct channel *req, int an_bit)
 	 * protected area is affected, because we may have to move processed
 	 * data later, which is much more complicated.
 	 */
-	if (buffer_not_empty(req->buf) && msg->msg_state < HTTP_MSG_ERROR) {
+	if (c_data(req) && msg->msg_state < HTTP_MSG_ERROR) {
 		if (txn->flags & TX_NOT_FIRST) {
 			if (unlikely(!channel_is_rewritable(req))) {
 				if (req->flags & (CF_SHUTW|CF_SHUTW_NOW|CF_WRITE_ERROR|CF_WRITE_TIMEOUT))
@@ -4142,7 +4142,7 @@ int http_wait_for_request_body(struct stream *s, struct channel *req, int an_bit
 		 * TRAILERS state.
 		 */
 		unsigned int chunk;
-		int ret = h1_parse_chunk_size(req->buf, co_data(req) + msg->next, b_data(req->buf), &chunk);
+		int ret = h1_parse_chunk_size(req->buf, co_data(req) + msg->next, c_data(req), &chunk);
 
 		if (!ret)
 			goto missing_data;
@@ -5126,7 +5126,7 @@ int http_wait_for_response(struct stream *s, struct channel *rep, int an_bit)
 	 * protected area is affected, because we may have to move processed
 	 * data later, which is much more complicated.
 	 */
-	if (buffer_not_empty(rep->buf) && msg->msg_state < HTTP_MSG_ERROR) {
+	if (c_data(rep) && msg->msg_state < HTTP_MSG_ERROR) {
 		if (unlikely(!channel_is_rewritable(rep))) {
 			/* some data has still not left the buffer, wake us once that's done */
 			if (rep->flags & (CF_SHUTW|CF_SHUTW_NOW|CF_WRITE_ERROR|CF_WRITE_TIMEOUT))
@@ -6353,7 +6353,7 @@ http_msg_forward_chunked_body(struct stream *s, struct http_msg *msg)
 
 		case HTTP_MSG_CHUNK_CRLF:
 			/* we want the CRLF after the data */
-			ret = h1_skip_chunk_crlf(chn->buf, co_data(chn) + msg->next, b_data(chn->buf));
+			ret = h1_skip_chunk_crlf(chn->buf, co_data(chn) + msg->next, c_data(chn));
 			if (ret == 0)
 				goto missing_data_or_waiting;
 			if (ret < 0) {
@@ -6371,7 +6371,7 @@ http_msg_forward_chunked_body(struct stream *s, struct http_msg *msg)
 			 * then set ->next to point to the body and switch to
 			 * DATA or TRAILERS state.
 			 */
-			ret = h1_parse_chunk_size(chn->buf, co_data(chn) + msg->next, b_data(chn->buf), &chunk);
+			ret = h1_parse_chunk_size(chn->buf, co_data(chn) + msg->next, c_data(chn), &chunk);
 			if (ret == 0)
 				goto missing_data_or_waiting;
 			if (ret < 0) {
diff --git a/src/stream_interface.c b/src/stream_interface.c
index 2677b2f0c..6542f9f93 100644
--- a/src/stream_interface.c
+++ b/src/stream_interface.c
@@ -1115,7 +1115,7 @@ static void si_cs_recv_cb(struct conn_stream *cs)
 	if (conn->xprt->rcv_pipe && conn->mux->rcv_pipe &&
 	    (ic->pipe || ic->to_forward >= MIN_SPLICE_FORWARD) &&
 	    ic->flags & CF_KERN_SPLICING) {
-		if (buffer_not_empty(ic->buf)) {
+		if (c_data(ic)) {
 			/* We're embarrassed, there are already data pending in
 			 * the buffer and we don't want to have them at two
 			 * locations at a time. Let's indicate we need some