diff --git a/completion/zsh/_ubanner b/completion/zsh/_ubanner
index 669d47e..6754938 100644
--- a/completion/zsh/_ubanner
+++ b/completion/zsh/_ubanner
@@ -3,6 +3,8 @@
 # Copyright © 2024 Christopher Bock <christopher@bocki.com>
 # SPDX-License-Identifier: MIT
 
+# SHA-256(help) = 3b402f915db43ab07d8699098cf5746bc6ce7768d32cf74cc9dac4b5ea3ee78b
+
 local arguments
 
 arguments=(
diff --git a/doc/ubanner.1 b/doc/ubanner.1
index 4df4724..696c456 100644
--- a/doc/ubanner.1
+++ b/doc/ubanner.1
@@ -1,6 +1,8 @@
 .\" Copyright © 2024 Jakub Wilk <jwilk@jwilk.net>
 .\" SPDX-License-Identifier: MIT
 
+.\" SHA-256(help) = 3b402f915db43ab07d8699098cf5746bc6ce7768d32cf74cc9dac4b5ea3ee78b
+
 .TH UBANNER 1 2024-03-23 "ubanner 0.1"
 .SH NAME
 ubanner \- Unicode-enabled banner(1)-like program
diff --git a/t/help.t b/t/help.t
index 0b73210..1191299 100755
--- a/t/help.t
+++ b/t/help.t
@@ -7,7 +7,7 @@ set -e -u
 
 . "${0%/*}/common.sh"
 
-echo 1..1
+echo 1..3
 xout=$(
     < "$dir/README" \
     grep '^   [$] ubanner --help$' -A999 |
@@ -28,5 +28,25 @@ else
     sed -e 's/^/# /' <<< "$diff"
     echo 'not ok 1'
 fi
+xsum=$(sha256sum <<< "$out")
+xsum=${xsum%% *}
+var='SHA-256(help)'
+echo "# $var = $xsum"
+declare -i n=2
+t_sync()
+{
+    path="$1"
+    line=$(grep -F " $var = " < "$dir/$path")
+    sum=${line##*" $var = "}
+    if [[ $sum = $xsum ]]
+    then
+        echo ok $n "$path"
+    else
+        echo not ok $n "$path"
+    fi
+    n+=1
+}
+t_sync 'completion/zsh/_ubanner'
+t_sync 'doc/ubanner.1'
 
 # vim:ts=4 sts=4 sw=4 et ft=sh