diff --git a/t/perf/perf-lib.sh b/t/perf/perf-lib.sh
index 5580c22812be1cadd6b70974eb85ce7cda1b8df3..a1361e530c60609a52948dd0fd35642d57f84486 100644
--- a/t/perf/perf-lib.sh
+++ b/t/perf/perf-lib.sh
@@ -163,7 +163,7 @@ test_perf () {
 		else
 			echo "perf $test_count - $1:"
 		fi
-		for i in $(seq 1 $GIT_PERF_REPEAT_COUNT); do
+		for i in $(test_seq 1 $GIT_PERF_REPEAT_COUNT); do
 			say >&3 "running: $2"
 			if test_run_perf_ "$2"
 			then
diff --git a/t/t5551-http-fetch.sh b/t/t5551-http-fetch.sh
index fadf2f258ea5305fb52d418a6409fb07889bc205..91eaf53d1d30f7719e93e88b674f60b6c6eaa376 100755
--- a/t/t5551-http-fetch.sh
+++ b/t/t5551-http-fetch.sh
@@ -114,7 +114,7 @@ test -n "$GIT_TEST_LONG" && test_set_prereq EXPENSIVE
 test_expect_success EXPENSIVE 'create 50,000 tags in the repo' '
 	(
 	cd "$HTTPD_DOCUMENT_ROOT_PATH/repo.git" &&
-	for i in `seq 50000`
+	for i in `test_seq 50000`
 	do
 		echo "commit refs/heads/too-many-refs"
 		echo "mark :$i"
diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
index 80daaca7806cbe1a6de0ddeba40400c8a811328e..9096398b184df722492cd6072d618edb78eb5206 100644
--- a/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh
@@ -530,6 +530,27 @@ test_cmp() {
 	$GIT_TEST_CMP "$@"
 }
 
+# Print a sequence of numbers or letters in increasing order.  This is
+# similar to GNU seq(1), but the latter might not be available
+# everywhere (and does not do letters).  It may be used like:
+#
+#	for i in `test_seq 100`; do
+#		for j in `test_seq 10 20`; do
+#			for k in `test_seq a z`; do
+#				echo $i-$j-$k
+#			done
+#		done
+#	done
+
+test_seq () {
+	case $# in
+	1)	set 1 "$@" ;;
+	2)	;;
+	*)	error "bug in the test script: not 1 or 2 parameters to test_seq" ;;
+	esac
+	"$PERL_PATH" -le 'print for $ARGV[0]..$ARGV[1]' -- "$@"
+}
+
 # This function can be used to schedule some commands to be run
 # unconditionally at the end of the test to restore sanity:
 #