diff --git a/sloth/items/factory.py b/sloth/items/factory.py
index d3b8195..d622819 100644
--- a/sloth/items/factory.py
+++ b/sloth/items/factory.py
@@ -32,6 +32,7 @@ class Factory:
         item: python callable or string
             Reference to the callable which creates the new object.
         """
+        _type = str(_type)
         if _type in self.items_ and not replace:
             raise Exception("Type %s already has an item: %s" % \
                              (_type, str(self.items_[_type])))
@@ -50,6 +51,7 @@ class Factory:
             Type for which the mapping should be removed.  If None, all
             mappings will be removed.
         """
+        _type = str(_type)
         if _type is None:
             self.items_     = {}
         else:
@@ -73,6 +75,7 @@ class Factory:
         Newly created object. If for the given type no mapping exists, this
         function returns ``None``.
         """
+        _type = str(_type)
         if _type not in self.items_:
             return None
         item = self.items_[_type]