diff --git a/modules/aeolus/datasource.py b/modules/aeolus/datasource.py
index c936fbcd2c6c508b9a275690c0aa1f90f3bd6b61..5795c9be1fcc00116a69ef98fd612edcda51e1d0 100644
--- a/modules/aeolus/datasource.py
+++ b/modules/aeolus/datasource.py
@@ -202,8 +202,8 @@ class CLAVRx_CALIPSO(Files):
 
 
 class CLAVRx_VIIRS(Files):
-    def __init__(self, files_path):
-        super().__init__(files_path, 5, 'clavrx*viirs*level2.??')
+    def __init__(self, files_path, pattern='clavrx*viirs*level2.??'):
+        super().__init__(files_path, 5, pattern)
         self.params = get_parameters_clavrx()
 
     def get_datetime(self, pathname):