diff --git a/include/haproxy/ring-t.h b/include/haproxy/ring-t.h
index b89c88695..55867b54b 100644
--- a/include/haproxy/ring-t.h
+++ b/include/haproxy/ring-t.h
@@ -27,7 +27,7 @@
 #include <haproxy/thread.h>
 
 /* The code below handles circular buffers with single-producer and multiple
- * readers (up to 255). The buffer storage area must remain always allocated.
+ * readers (up to 254). The buffer storage area must remain always allocated.
  * It's made of series of payload blocks followed by a readers count (RC).
  * There is always a readers count at the beginning of the buffer as well. Each
  * payload block is composed of a varint-encoded size (VI) followed by the
@@ -96,6 +96,10 @@
 #define RING_WF_WAIT_MODE  0x00000001   /* wait for new contents */
 #define RING_WF_SEEK_NEW   0x00000002   /* seek to new contents  */
 
+/* keep values below in decimal, they may be dumped in error messages */
+#define RING_WRITING_SIZE  255  /* the next message's size is being written */
+#define RING_MAX_READERS   254  /* highest supported value for RC */
+
 struct ring {
 	struct buffer buf;   // storage area
 	struct list waiters; // list of waiters, for now, CLI "show event"
diff --git a/src/ring.c b/src/ring.c
index c1e748476..95e1e991f 100644
--- a/src/ring.c
+++ b/src/ring.c
@@ -270,7 +270,7 @@ int ring_attach(struct ring *ring)
 	int users = ring->readers_count;
 
 	do {
-		if (users >= 255)
+		if (users >= RING_MAX_READERS)
 			return 0;
 	} while (!_HA_ATOMIC_CAS(&ring->readers_count, &users, users + 1));
 	return 1;
@@ -313,7 +313,7 @@ int ring_attach_cli(struct ring *ring, struct appctx *appctx, uint flags)
 
 	if (!ring_attach(ring))
 		return cli_err(appctx,
-		               "Sorry, too many watchers (255) on this ring buffer. "
+		               "Sorry, too many watchers (" TOSTR(RING_MAX_READERS) ") on this ring buffer. "
 		               "What could it have so interesting to attract so many watchers ?");
 
 	if (!appctx->io_handler)