diff --git a/bitfield/forms.py b/bitfield/forms.py
index 352a558..a1f4bbc 100644
--- a/bitfield/forms.py
+++ b/bitfield/forms.py
@@ -41,3 +41,11 @@ def clean(self, value):
             except AttributeError:
                 raise ValidationError('Unknown choice: %r' % (k,))
         return int(result)
+        
+    def prepare_value(self, value):
+        if not value:
+            return []
+        try:
+            return BitHandler(value, [k for k, v in self.choices])
+        except TypeError:
+            return value