diff --git a/Makefile b/Makefile
index 9d8d350de..d77900931 100644
--- a/Makefile
+++ b/Makefile
@@ -213,7 +213,8 @@ SMALL_OPTS =
 # You can enable debugging on specific code parts by setting DEBUG=-DDEBUG_xxx.
 # Currently defined DEBUG macros include DEBUG_FULL, DEBUG_MEMORY, DEBUG_FSM,
 # DEBUG_HASH, DEBUG_AUTH, DEBUG_SPOE, DEBUG_UAF and DEBUG_THREAD, DEBUG_STRICT,
-# DEBUG_DEV. Please check sources for exact meaning or do not use at all.
+# DEBUG_DEV, DEBUG_FD. Please check sources for exact meaning or do not use at
+# all.
 DEBUG =
 
 #### Trace options
diff --git a/include/haproxy/fd-t.h b/include/haproxy/fd-t.h
index 97b383ceb..6ff8ef135 100644
--- a/include/haproxy/fd-t.h
+++ b/include/haproxy/fd-t.h
@@ -134,6 +134,9 @@ struct fdtab {
 	unsigned char cloned:1;              /* 1 if a cloned socket, requires EPOLL_CTL_DEL on close */
 	unsigned char initialized:1;         /* 1 if init phase was done on this fd (e.g. set non-blocking) */
 	unsigned char et_possible:1;         /* 1 if edge-triggered is possible on this FD */
+#ifdef DEBUG_FD
+	unsigned int event_count;            /* number of events reported */
+#endif
 } THREAD_ALIGNED(64);
 
 /* polled mask, one bit per thread and per direction for each FD */
diff --git a/include/haproxy/fd.h b/include/haproxy/fd.h
index f7af4e162..7b77567fa 100644
--- a/include/haproxy/fd.h
+++ b/include/haproxy/fd.h
@@ -446,6 +446,9 @@ static inline void fd_insert(int fd, void *owner, void (*iocb)(int fd), unsigned
 	fdtab[fd].linger_risk = 0;
 	fdtab[fd].cloned = 0;
 	fdtab[fd].et_possible = 0;
+#ifdef DEBUG_FD
+	fdtab[fd].event_count = 0;
+#endif
 
 	/* conn_fd_handler should support edge-triggered FDs */
 	if ((global.tune.options & GTUNE_FD_ET) && fdtab[fd].iocb == conn_fd_handler)
diff --git a/src/cli.c b/src/cli.c
index b8fac13a8..b9afc1b20 100644
--- a/src/cli.c
+++ b/src/cli.c
@@ -1002,7 +1002,14 @@ static int cli_io_handler_show_fd(struct appctx *appctx)
 
 		fdt = fdtab[fd];
 
-		if (!fdt.owner)
+		/* When DEBUG_FD is set, we also report closed FDs that have a
+		 * non-null event count to detect stuck ones.
+		 */
+		if (!fdt.owner
+#ifdef DEBUG_FD
+		    && !fdt.event_count
+#endif
+		    )
 			goto skip; // closed
 
 		if (fdt.iocb == conn_fd_handler) {
@@ -1038,7 +1045,10 @@ static int cli_io_handler_show_fd(struct appctx *appctx)
 			     fdt.iocb);
 		resolve_sym_name(&trash, NULL, fdt.iocb);
 
-		if (fdt.iocb == conn_fd_handler) {
+		if (!fdt.owner) {
+			chunk_appendf(&trash, ")");
+		}
+		else if (fdt.iocb == conn_fd_handler) {
 			chunk_appendf(&trash, ") back=%d cflg=0x%08x", is_back, conn_flags);
 			if (px)
 				chunk_appendf(&trash, " px=%s", px->id);
@@ -1061,6 +1071,9 @@ static int cli_io_handler_show_fd(struct appctx *appctx)
 			              li->bind_conf->frontend->id);
 		}
 
+#ifdef DEBUG_FD
+		chunk_appendf(&trash, " evcnt=%u", fdtab[fd].event_count);
+#endif
 		chunk_appendf(&trash, ")\n");
 
 		if (ci_putchk(si_ic(si), &trash) == -1) {
diff --git a/src/ev_epoll.c b/src/ev_epoll.c
index 92c000f85..ba7f2e030 100644
--- a/src/ev_epoll.c
+++ b/src/ev_epoll.c
@@ -222,6 +222,9 @@ static void _do_poll(struct poller *p, int exp, int wake)
 		e = epoll_events[count].events;
 		fd = epoll_events[count].data.fd;
 
+#ifdef DEBUG_FD
+		_HA_ATOMIC_ADD(&fdtab[fd].event_count, 1);
+#endif
 		if (!fdtab[fd].owner) {
 			activity[tid].poll_dead_fd++;
 			continue;
diff --git a/src/ev_evports.c b/src/ev_evports.c
index a00813584..2ad546ff8 100644
--- a/src/ev_evports.c
+++ b/src/ev_evports.c
@@ -216,6 +216,9 @@ static void _do_poll(struct poller *p, int exp, int wake)
 		fd = evports_evlist[i].portev_object;
 		events = evports_evlist[i].portev_events;
 
+#ifdef DEBUG_FD
+		_HA_ATOMIC_ADD(&fdtab[fd].event_count, 1);
+#endif
 		if (fdtab[fd].owner == NULL) {
 			activity[tid].poll_dead_fd++;
 			continue;
diff --git a/src/ev_kqueue.c b/src/ev_kqueue.c
index 539394e7f..a67d05b26 100644
--- a/src/ev_kqueue.c
+++ b/src/ev_kqueue.c
@@ -183,6 +183,9 @@ static void _do_poll(struct poller *p, int exp, int wake)
 		unsigned int n = 0;
 		fd = kev[count].ident;
 
+#ifdef DEBUG_FD
+		_HA_ATOMIC_ADD(&fdtab[fd].event_count, 1);
+#endif
 		if (!fdtab[fd].owner) {
 			activity[tid].poll_dead_fd++;
 			continue;
diff --git a/src/ev_poll.c b/src/ev_poll.c
index e63334e14..b0b0e2bc4 100644
--- a/src/ev_poll.c
+++ b/src/ev_poll.c
@@ -219,6 +219,9 @@ static void _do_poll(struct poller *p, int exp, int wake)
 		int e = poll_events[count].revents;
 		fd = poll_events[count].fd;
 
+#ifdef DEBUG_FD
+		_HA_ATOMIC_ADD(&fdtab[fd].event_count, 1);
+#endif
 		if (!(e & ( POLLOUT | POLLIN | POLLERR | POLLHUP | POLLRDHUP )))
 			continue;
 
diff --git a/src/ev_select.c b/src/ev_select.c
index 544b7f211..aca1ea8ec 100644
--- a/src/ev_select.c
+++ b/src/ev_select.c
@@ -197,6 +197,9 @@ static void _do_poll(struct poller *p, int exp, int wake)
 		for (count = BITS_PER_INT, fd = fds * BITS_PER_INT; count && fd < maxfd; count--, fd++) {
 			unsigned int n = 0;
 
+#ifdef DEBUG_FD
+			_HA_ATOMIC_ADD(&fdtab[fd].event_count, 1);
+#endif
 			if (!fdtab[fd].owner) {
 				activity[tid].poll_dead_fd++;
 				continue;
diff --git a/src/fd.c b/src/fd.c
index 60ad69901..bf2383e4d 100644
--- a/src/fd.c
+++ b/src/fd.c
@@ -322,6 +322,9 @@ static void fd_dodelete(int fd, int do_close)
 
 	fdtab[fd].state = 0;
 
+#ifdef DEBUG_FD
+	fdtab[fd].event_count = 0;
+#endif
 	port_range_release_port(fdinfo[fd].port_range, fdinfo[fd].local_port);
 	fdinfo[fd].port_range = NULL;
 	fdtab[fd].owner = NULL;