diff --git a/helper/is-git-repo b/helper/is-git-repo
index cf03a16..869c2e3 100755
--- a/helper/is-git-repo
+++ b/helper/is-git-repo
@@ -3,7 +3,9 @@
 #
 
 is_git_repo() {
-  git rev-parse --show-toplevel > /dev/null 2>&1
+  # --git-dir succeeds for both normal and bare repositories, whereas
+  # --show-toplevel fails inside a bare repository (it has no working tree).
+  git rev-parse --git-dir > /dev/null 2>&1
   result=$?
   if test $result != 0; then
     >&2 echo 'Not a git repo!'
diff --git a/scripts/checkstyle.py b/scripts/checkstyle.py
index 88a875c..8a26901 100755
--- a/scripts/checkstyle.py
+++ b/scripts/checkstyle.py
@@ -3,7 +3,7 @@ import argparse
 import os
 import re
 import sys
-from collections.abc import Callable  # Compatibility.
+from collections.abc import Callable  # compat
 from pathlib import Path
 from typing import Any
 
@@ -102,13 +102,12 @@ def lintfile(file: Path, rules: list[Rule], options: dict[str, Any]):
 
         for rule in rules:
             should_run = False
-            # ruff: noqa: SIM102
-            if 'sh' in rule['fileTypes']:
-                if file.name.endswith('.sh'):
-                    should_run = True
-            if 'bash' in rule['fileTypes']:
-                if file.name.endswith('.bash') or file.name.endswith('.bats') or file.name.startswith('git-'):
-                    should_run = True
+            if 'sh' in rule['fileTypes'] and file.name.endswith('.sh'):
+                should_run = True
+            if 'bash' in rule['fileTypes'] and (
+                file.name.endswith('.bash') or file.name.endswith('.bats') or file.name.startswith('git-')
+            ):
+                should_run = True
 
             if options['verbose']:
                 print(f'{file!s}: {should_run}')
diff --git a/tests/is-git-repo.bats b/tests/is-git-repo.bats
new file mode 100644
index 0000000..118d487
--- /dev/null
+++ b/tests/is-git-repo.bats
@@ -0,0 +1,32 @@
+# shellcheck shell=bash
+
+source "$BATS_TEST_DIRNAME/test_util.sh"
+
+setup_file() {
+	test_util.setup_file
+}
+
+setup() {
+	test_util.cd_test
+}
+
+@test "is_git_repo succeeds inside a normal (non-bare) repository" {
+	test_util.git_init
+
+	run bash "$BATS_TEST_DIRNAME/../helper/is-git-repo"
+	assert_success
+}
+
+@test "is_git_repo succeeds inside a bare repository (see #1238)" {
+	git init --bare --initial-branch main repo.git
+	cd repo.git
+
+	run bash "$BATS_TEST_DIRNAME/../helper/is-git-repo"
+	assert_success
+}
+
+@test "is_git_repo fails outside of a repository" {
+	run bash "$BATS_TEST_DIRNAME/../helper/is-git-repo"
+	assert_failure
+	assert_output 'Not a git repo!'
+}