diff --git a/bitfield/forms.py b/bitfield/forms.py
index 6340548..961f818 100644
--- a/bitfield/forms.py
+++ b/bitfield/forms.py
@@ -28,12 +28,11 @@ def _has_changed(self, initial, data):
 
 class BitFormField(IntegerField):
     def __init__(self, choices=(), widget=BitFieldCheckboxSelectMultiple, *args, **kwargs):
-
-        if isinstance(kwargs['initial'], int):
-            iv = kwargs['initial']
+        initial = kwargs.get('initial')
+        if isinstance(initial, int):
             l = []
             for i in range(0, 63):
-                if (1 << i) & iv > 0:
+                if (1 << i) & initial > 0:
                     l += [choices[i][0]]
             kwargs['initial'] = l
         self.widget = widget