diff --git a/t/perf/perf-lib.sh b/t/perf/perf-lib.sh
index 11d1922cf5..2e33ab3ec3 100644
--- a/t/perf/perf-lib.sh
+++ b/t/perf/perf-lib.sh
@@ -82,7 +82,7 @@ test_perf_do_repo_symlink_config_ () {
 
 test_perf_create_repo_from () {
 	test "$#" = 2 ||
-	error "bug in the test script: not 2 parameters to test-create-repo"
+	BUG "not 2 parameters to test-create-repo"
 	repo="$1"
 	source="$2"
 	source_git="$("$MODERN_GIT" -C "$source" rev-parse --git-dir)"
@@ -184,7 +184,7 @@ test_wrapper_ () {
 	test_start_
 	test "$#" = 3 && { test_prereq=$1; shift; } || test_prereq=
 	test "$#" = 2 ||
-	error "bug in the test script: not 2 or 3 parameters to test-expect-success"
+	BUG "not 2 or 3 parameters to test-expect-success"
 	export test_prereq
 	if ! test_skip "$@"
 	then
diff --git a/t/t0001-init.sh b/t/t0001-init.sh
index 182da069f1..42a263cada 100755
--- a/t/t0001-init.sh
+++ b/t/t0001-init.sh
@@ -319,14 +319,14 @@ test_lazy_prereq GETCWD_IGNORES_PERMS '
 	base=GETCWD_TEST_BASE_DIR &&
 	mkdir -p $base/dir &&
 	chmod 100 $base ||
-	error "bug in test script: cannot prepare $base"
+	BUG "cannot prepare $base"
 
 	(cd $base/dir && /bin/pwd -P)
 	status=$?
 
 	chmod 700 $base &&
 	rm -rf $base ||
-	error "bug in test script: cannot clean $base"
+	BUG "cannot clean $base"
 	return $status
 '
 
diff --git a/t/t4013-diff-various.sh b/t/t4013-diff-various.sh
index 73f7038253..7d985ff6b1 100755
--- a/t/t4013-diff-various.sh
+++ b/t/t4013-diff-various.sh
@@ -129,7 +129,7 @@ do
 		case "$magic" in
 		noellipses) ;;
 		*)
-			die "bug in t4103: unknown magic $magic" ;;
+			BUG "unknown magic $magic" ;;
 		esac ;;
 	*)
 		cmd="$magic $cmd" magic=
diff --git a/t/t5516-fetch-push.sh b/t/t5516-fetch-push.sh
index 7316365a24..37e8e80893 100755
--- a/t/t5516-fetch-push.sh
+++ b/t/t5516-fetch-push.sh
@@ -95,7 +95,7 @@ mk_child() {
 
 check_push_result () {
 	test $# -ge 3 ||
-	error "bug in the test script: check_push_result requires at least 3 parameters"
+	BUG "check_push_result requires at least 3 parameters"
 
 	repo_name="$1"
 	shift
diff --git a/t/t9902-completion.sh b/t/t9902-completion.sh
index 3c6b185b60..d01ad8eb25 100755
--- a/t/t9902-completion.sh
+++ b/t/t9902-completion.sh
@@ -1249,7 +1249,7 @@ test_expect_success 'teardown after ref completion' '
 
 test_path_completion ()
 {
-	test $# = 2 || error "bug in the test script: not 2 parameters to test_path_completion"
+	test $# = 2 || BUG "not 2 parameters to test_path_completion"
 
 	local cur="$1" expected="$2"
 	echo "$expected" >expected &&
diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
index b4e391526a..3c6bf8d855 100644
--- a/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh
@@ -418,14 +418,14 @@ test_declared_prereq () {
 test_verify_prereq () {
 	test -z "$test_prereq" ||
 	expr >/dev/null "$test_prereq" : '[A-Z0-9_,!]*$' ||
-	error "bug in the test script: '$test_prereq' does not look like a prereq"
+	BUG "'$test_prereq' does not look like a prereq"
 }
 
 test_expect_failure () {
 	test_start_
 	test "$#" = 3 && { test_prereq=$1; shift; } || test_prereq=
 	test "$#" = 2 ||
-	error "bug in the test script: not 2 or 3 parameters to test-expect-failure"
+	BUG "not 2 or 3 parameters to test-expect-failure"
 	test_verify_prereq
 	export test_prereq
 	if ! test_skip "$@"
@@ -445,7 +445,7 @@ test_expect_success () {
 	test_start_
 	test "$#" = 3 && { test_prereq=$1; shift; } || test_prereq=
 	test "$#" = 2 ||
-	error "bug in the test script: not 2 or 3 parameters to test-expect-success"
+	BUG "not 2 or 3 parameters to test-expect-success"
 	test_verify_prereq
 	export test_prereq
 	if ! test_skip "$@"
@@ -472,7 +472,7 @@ test_expect_success () {
 test_external () {
 	test "$#" = 4 && { test_prereq=$1; shift; } || test_prereq=
 	test "$#" = 3 ||
-	error >&5 "bug in the test script: not 3 or 4 parameters to test_external"
+	BUG "not 3 or 4 parameters to test_external"
 	descr="$1"
 	shift
 	test_verify_prereq
@@ -613,7 +613,7 @@ test_path_is_missing () {
 test_line_count () {
 	if test $# != 3
 	then
-		error "bug in the test script: not 3 parameters to test_line_count"
+		BUG "not 3 parameters to test_line_count"
 	elif ! test $(wc -l <"$3") "$1" "$2"
 	then
 		echo "test_line_count: line count for $3 !$1 $2"
@@ -793,13 +793,12 @@ test_i18ngrep () {
 	eval "last_arg=\${$#}"
 
 	test -f "$last_arg" ||
-	error "bug in the test script: test_i18ngrep requires a file" \
-	      "to read as the last parameter"
+	BUG "test_i18ngrep requires a file to read as the last parameter"
 
 	if test $# -lt 2 ||
 	   { test "x!" = "x$1" && test $# -lt 3 ; }
 	then
-		error "bug in the test script: too few parameters to test_i18ngrep"
+		BUG "too few parameters to test_i18ngrep"
 	fi
 
 	if test_have_prereq !C_LOCALE_OUTPUT
@@ -871,7 +870,7 @@ test_seq () {
 	case $# in
 	1)	set 1 "$@" ;;
 	2)	;;
-	*)	error "bug in the test script: not 1 or 2 parameters to test_seq" ;;
+	*)	BUG "not 1 or 2 parameters to test_seq" ;;
 	esac
 	test_seq_counter__=$1
 	while test "$test_seq_counter__" -le "$2"
@@ -909,7 +908,7 @@ test_when_finished () {
 	# doing so on Bash is better than nothing (the test will
 	# silently pass on other shells).
 	test "${BASH_SUBSHELL-0}" = 0 ||
-	error "bug in test script: test_when_finished does nothing in a subshell"
+	BUG "test_when_finished does nothing in a subshell"
 	test_cleanup="{ $*
 		} && (exit \"\$eval_ret\"); eval_ret=\$?; $test_cleanup"
 }
@@ -918,7 +917,7 @@ test_when_finished () {
 # Usage: test_create_repo <directory>
 test_create_repo () {
 	test "$#" = 1 ||
-	error "bug in the test script: not 1 parameter to test-create-repo"
+	BUG "not 1 parameter to test-create-repo"
 	repo="$1"
 	mkdir -p "$repo"
 	(
@@ -1231,7 +1230,7 @@ test_oid_cache () {
 
 		if ! expr "$k" : '[a-z0-9][a-z0-9]*$' >/dev/null
 		then
-			error 'bug in the test script: bad hash algorithm'
+			BUG 'bad hash algorithm'
 		fi &&
 		eval "test_oid_${k}_$tag=\"\$v\""
 	done
@@ -1246,7 +1245,7 @@ test_oid () {
 	# key-hash pair, so exit with an error.
 	if eval "test -z \"\${$var+set}\""
 	then
-		error "bug in the test script: undefined key '$1'" >&2
+		BUG "undefined key '$1'"
 	fi &&
 	eval "printf '%s' \"\${$var}\""
 }
diff --git a/t/test-lib.sh b/t/test-lib.sh
index 6c6c0af7a1..0f1faa24b2 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -402,6 +402,10 @@ error () {
 	exit 1
 }
 
+BUG () {
+	error >&7 "bug in the test script: $*"
+}
+
 say () {
 	say_color info "$*"
 }
@@ -729,7 +733,7 @@ test_run_ () {
 		if $(printf '%s\n' "$1" | sed -f "$GIT_BUILD_DIR/t/chainlint.sed" | grep -q '?![A-Z][A-Z]*?!') ||
 			test "OK-117" != "$(test_eval_ "(exit 117) && $1${LF}${LF}echo OK-\$?" 3>&1)"
 		then
-			error "bug in the test script: broken &&-chain or run-away HERE-DOC: $1"
+			BUG "broken &&-chain or run-away HERE-DOC: $1"
 		fi
 		trace=$trace_tmp
 	fi
@@ -1231,7 +1235,7 @@ test_lazy_prereq SANITY '
 	chmod -w SANETESTD.1 &&
 	chmod -r SANETESTD.1/x &&
 	chmod -rx SANETESTD.2 ||
-	error "bug in test sript: cannot prepare SANETESTD"
+	BUG "cannot prepare SANETESTD"
 
 	! test -r SANETESTD.1/x &&
 	! rm SANETESTD.1/x && ! test -f SANETESTD.2/x
@@ -1239,7 +1243,7 @@ test_lazy_prereq SANITY '
 
 	chmod +rwx SANETESTD.1 SANETESTD.2 &&
 	rm -rf SANETESTD.1 SANETESTD.2 ||
-	error "bug in test sript: cannot clean SANETESTD"
+	BUG "cannot clean SANETESTD"
 	return $status
 '