diff --git a/tests/test_file_utils.py b/tests/test_file_utils.py
index 6e475009..ad18d2f1 100644
--- a/tests/test_file_utils.py
+++ b/tests/test_file_utils.py
@@ -39,7 +39,7 @@ def test_find_most_recent_file(self):
             mock_datetime.now.return_value = mock_current_time
 
             # Call the function with the temporary folder
-            result = find_most_recent_file(self.temp_folder)
+            result = find_most_recent_file(self.temp_folder, file_ext='.txt')
 
         # Expect the most recent file to be the first in the list (modified 1 day ago)
         expected_result = os.path.join(self.temp_folder, "test_file_1.txt")