diff --git a/regress/control-client-wait-exit.sh b/regress/control-client-wait-exit.sh
new file mode 100644
index 000000000..63739b284
--- /dev/null
+++ b/regress/control-client-wait-exit.sh
@@ -0,0 +1,63 @@
+#!/bin/sh
+
+# A control client with the wait-exit flag lingers after %exit until its input
+# sends an empty line or closes. The terminating empty line must be honoured
+# even when several lines arrive in a single read (as from a pipe or a raw
+# terminal): reading input with stdio would pull them all into the FILE buffer
+# and leave the empty line where poll never sees it, hanging the client.
+
+PATH=/bin:/usr/bin
+TERM=screen
+
+[ -z "$TEST_TMUX" ] && TEST_TMUX=$(readlink -f ../tmux)
+TMUX="$TEST_TMUX -Ltest"
+$TMUX kill-server 2>/dev/null
+
+FIFO=$(mktemp -u)
+OUT=$(mktemp)
+mkfifo "$FIFO" || exit 1
+trap "$TMUX kill-server 2>/dev/null; rm -f $FIFO $OUT" 0 1 15
+
+# Start a control client that reads its input from the fifo. Keep the write
+# end open (fd 3) so the client never sees EOF: it must exit on the empty
+# line, not on the pipe closing.
+$TMUX -f/dev/null -C new -s wait-exit <"$FIFO" >"$OUT" 2>&1 &
+CLIENT=$!
+exec 3>"$FIFO"
+sleep 1
+
+# Ask to linger after exit, then detach so the client prints %exit and enters
+# the wait-exit loop.
+printf 'refresh-client -f wait-exit\n' >&3
+sleep 1
+$TMUX detach-client -s wait-exit
+
+# Wait for the client to print %exit and enter the wait-exit loop.
+i=0
+while [ $i -lt 5 ]; do
+	grep -q '^%exit' "$OUT" && break
+	sleep 1
+	i=$((i + 1))
+done
+grep -q '^%exit' "$OUT" || exit 1
+
+# Deliver the terminating empty line in one write, after a non-empty line, so
+# a single read returns "a\n" and "\n" together. The empty line must still end
+# the wait.
+printf 'a\n\n' >&3
+
+# The client should exit promptly. If it is still alive after the timeout the
+# empty line was lost in a buffer and the client has hung.
+i=0
+while [ $i -lt 10 ]; do
+	kill -0 $CLIENT 2>/dev/null || break
+	sleep 1
+	i=$((i + 1))
+done
+if kill -0 $CLIENT 2>/dev/null; then
+	kill $CLIENT 2>/dev/null
+	exit 1
+fi
+exec 3>&-
+
+exit 0