diff --git a/tests/scripts/check_test_cases.py b/tests/scripts/check_test_cases.py
index 0ca0def..8d7e8ba 100755
--- a/tests/scripts/check_test_cases.py
+++ b/tests/scripts/check_test_cases.py
@@ -102,9 +102,8 @@
     def walk_ssl_opt_sh(self, file_name):
         """Iterate over the test cases in ssl-opt.sh or a file with a similar format."""
         descriptions = self.new_per_file_state() # pylint: disable=assignment-from-none
-        listed = subprocess.run([f'{file_name}', '-l'],
-                                 capture_output=True)
-        listed = set(map(lambda x: x.rstrip(), listed.stdout.splitlines()))
+        listed = subprocess.check_output([f'{file_name}', '-l'])
+        listed = set(map(lambda x: x.rstrip(), listed.splitlines()))
         for description in listed:
             self.process_test_case(descriptions, file_name, None, description)