diff --git a/pynames/from_list_generator.py b/pynames/from_list_generator.py
index dcf0211..3418218 100644
--- a/pynames/from_list_generator.py
+++ b/pynames/from_list_generator.py
@@ -9,6 +9,7 @@ class FromListGenerator(BaseGenerator):
     SOURCE = None
 
     def __init__(self):
+        super(FromListGenerator, self).__init__()
         self.names_list = []
         self.choices = {}
 
@@ -24,7 +25,8 @@ class FromListGenerator(BaseGenerator):
         if not self.names_list:
             raise PynamesException('FromListGenerator: no names loaded from "%s"' % self.SOURCE)
 
-    def _get_cache_key(self, genders):
+    @staticmethod
+    def _get_cache_key(genders):
         return '_'.join(genders)
 
     def _get_slice(self, genders):
diff --git a/pynames/from_tables_generator.py b/pynames/from_tables_generator.py
index d5221bf..19f8fe7 100644
--- a/pynames/from_tables_generator.py
+++ b/pynames/from_tables_generator.py
@@ -41,6 +41,7 @@ class FromTablesGenerator(BaseGenerator):
     SOURCE = None
 
     def __init__(self):
+        super(FromTablesGenerator, self).__init__()
         self.templates_choices = {}
         self.templates = []
         self.tables = {}
@@ -57,7 +58,8 @@ class FromTablesGenerator(BaseGenerator):
                                for template_name, template_data in data['templates'].items() ]
             self.tables = data['tables']
 
-    def _get_templates_cache_key(self, genders):
+    @staticmethod
+    def _get_templates_cache_key(genders):
         return 't:%s' % '_'.join(genders)
 
     def _get_templates_slice(self, genders):