diff --git a/tests/syntax-tests/create_highlighted_versions.py b/tests/syntax-tests/create_highlighted_versions.py
index 70e5048a..a8d0bc78 100755
--- a/tests/syntax-tests/create_highlighted_versions.py
+++ b/tests/syntax-tests/create_highlighted_versions.py
@@ -30,9 +30,10 @@ def get_options(source):
     options_file = path.join(source_dirpath, "bat_options")
     try:
         with open(options_file, "r") as f:
-            options += list(map(lambda x: x.rstrip(), f.readlines()))
+            options.extend(map(lambda x: x.rstrip(), f.readlines()))
     except FileNotFoundError:
         pass
+
     return options