diff --git a/reclass/core.py b/reclass/core.py
index b07c5b2..488ee49 100644
--- a/reclass/core.py
+++ b/reclass/core.py
@@ -25,10 +25,10 @@
         self._ignore_class_notfound = ignore_class_notfound
         self._input_data = input_data
 
-        if type(ignore_class_regexp) == type(''):
-          self._ignore_class_regexp = [ignore_class_regexp]
+        if isinstance(ignore_class_regexp, basestring):
+            self._ignore_class_regexp = [ignore_class_regexp]
         else:
-          self._ignore_class_regexp = ignore_class_regexp
+            self._ignore_class_regexp = ignore_class_regexp
 
     @staticmethod
     def _get_timestamp():