diff --git a/Makefile b/Makefile
index 4ebbb6aa93..7b9668c1a7 100644
--- a/Makefile
+++ b/Makefile
@@ -742,6 +742,7 @@ TEST_BUILTINS_OBJS += test-dump-split-index.o
 TEST_BUILTINS_OBJS += test-dump-untracked-cache.o
 TEST_BUILTINS_OBJS += test-example-decorate.o
 TEST_BUILTINS_OBJS += test-genrandom.o
+TEST_BUILTINS_OBJS += test-genzeros.o
 TEST_BUILTINS_OBJS += test-hash.o
 TEST_BUILTINS_OBJS += test-hashmap.o
 TEST_BUILTINS_OBJS += test-hash-speed.o
diff --git a/t/helper/test-genzeros.c b/t/helper/test-genzeros.c
new file mode 100644
index 0000000000..f607f800a9
--- /dev/null
+++ b/t/helper/test-genzeros.c
@@ -0,0 +1,22 @@
+#include "test-tool.h"
+#include "git-compat-util.h"
+
+int cmd__genzeros(int argc, const char **argv)
+{
+	long count;
+
+	if (argc > 2) {
+		fprintf(stderr, "usage: %s [<count>]\n", argv[0]);
+		return 1;
+	}
+
+	count = argc > 1 ? strtol(argv[1], NULL, 0) : -1L;
+
+	while (count < 0 || count--) {
+		if (putchar(0) == EOF)
+			return -1;
+	}
+
+	return 0;
+}
+
diff --git a/t/helper/test-tool.c b/t/helper/test-tool.c
index f1cec235d3..716e8f679a 100644
--- a/t/helper/test-tool.c
+++ b/t/helper/test-tool.c
@@ -20,6 +20,7 @@ static struct test_cmd cmds[] = {
 	{ "dump-untracked-cache", cmd__dump_untracked_cache },
 	{ "example-decorate", cmd__example_decorate },
 	{ "genrandom", cmd__genrandom },
+	{ "genzeros", cmd__genzeros },
 	{ "hashmap", cmd__hashmap },
 	{ "hash-speed", cmd__hash_speed },
 	{ "iconv", cmd__iconv },
diff --git a/t/helper/test-tool.h b/t/helper/test-tool.h
index a2e0bd8cc9..f75e948a94 100644
--- a/t/helper/test-tool.h
+++ b/t/helper/test-tool.h
@@ -17,6 +17,7 @@ int cmd__dump_split_index(int argc, const char **argv);
 int cmd__dump_untracked_cache(int argc, const char **argv);
 int cmd__example_decorate(int argc, const char **argv);
 int cmd__genrandom(int argc, const char **argv);
+int cmd__genzeros(int argc, const char **argv);
 int cmd__hashmap(int argc, const char **argv);
 int cmd__hash_speed(int argc, const char **argv);
 int cmd__iconv(int argc, const char **argv);
diff --git a/t/t5562-http-backend-content-length.sh b/t/t5562-http-backend-content-length.sh
index bbadde2c6e..c0105423e6 100755
--- a/t/t5562-http-backend-content-length.sh
+++ b/t/t5562-http-backend-content-length.sh
@@ -143,7 +143,7 @@ test_expect_success GZIP 'push gzipped empty' '
 
 test_expect_success 'CONTENT_LENGTH overflow ssite_t' '
 	NOT_FIT_IN_SSIZE=$(ssize_b100dots) &&
-	generate_zero_bytes infinity  | env \
+	generate_zero_bytes | env \
 		CONTENT_TYPE=application/x-git-upload-pack-request \
 		QUERY_STRING=/repo.git/git-upload-pack \
 		PATH_TRANSLATED="$PWD"/.git/git-upload-pack \
diff --git a/t/test-lib-functions.sh b/t/test-lib-functions.sh
index f5a960b1e6..3e6410cc7c 100644
--- a/t/test-lib-functions.sh
+++ b/t/test-lib-functions.sh
@@ -120,13 +120,7 @@ remove_cr () {
 # If $1 is 'infinity', output forever or until the receiving pipe stops reading,
 # whichever comes first.
 generate_zero_bytes () {
-	perl -e 'if ($ARGV[0] == "infinity") {
-		while (-1) {
-			print "\0"
-		}
-	} else {
-		print "\0" x $ARGV[0]
-	}' "$@"
+	test-tool genzeros "$@"
 }
 
 # In some bourne shell implementations, the "unset" builtin returns