diff --git a/django/forms/fields.py b/django/forms/fields.py
index e3299c07aa..a5ea81d4b6 100644
--- a/django/forms/fields.py
+++ b/django/forms/fields.py
@@ -605,7 +605,7 @@ class BooleanField(Field):
         # will submit for False. Also check for '0', since this is what
         # RadioSelect will provide. Because bool("True") == bool('1') == True,
         # we don't need to handle that explicitly.
-        if value in ('False', '0'):
+        if isinstance(value, basestring) and value.lower() in ('false', '0'):
             value = False
         else:
             value = bool(value)
diff --git a/tests/regressiontests/forms/tests/fields.py b/tests/regressiontests/forms/tests/fields.py
index 59c761c76d..2303b4e9db 100644
--- a/tests/regressiontests/forms/tests/fields.py
+++ b/tests/regressiontests/forms/tests/fields.py
@@ -698,6 +698,8 @@ class FieldsTests(TestCase):
         self.assertEqual(False, f.clean('0'))
         self.assertEqual(True, f.clean('Django rocks'))
         self.assertEqual(False, f.clean('False'))
+        self.assertEqual(False, f.clean('false'))
+        self.assertEqual(False, f.clean('FaLsE'))
 
     # ChoiceField #################################################################