diff --git a/django/core/management/validation.py b/django/core/management/validation.py
index 68bfb6c..31a5604 100644
--- a/django/core/management/validation.py
+++ b/django/core/management/validation.py
@@ -51,6 +51,8 @@ def get_validation_errors(outfile, app=None):
                     from PIL import Image
                 except ImportError:
                     e.add(opts, '"%s": To use ImageFields, you need to install the Python Imaging Library. Get it at http://www.pythonware.com/products/pil/ .' % f.name)
+            if isinstance(f, models.BooleanField) and getattr(f, 'null', False):
+                e.add(opts, '"%s": BooleanFields cannot allow null values. Use NullBooleanField instead.' % f.name)
             if f.choices:
                 if isinstance(f.choices, basestring) or not is_iterable(f.choices):
                     e.add(opts, '"%s": "choices" should be iterable (e.g., a tuple or list).' % f.name)
diff --git a/tests/modeltests/invalid_models/models.py b/tests/modeltests/invalid_models/models.py
index 2817208..0fa4a7c 100644
--- a/tests/modeltests/invalid_models/models.py
+++ b/tests/modeltests/invalid_models/models.py
@@ -14,6 +14,7 @@ class FieldErrors(models.Model):
     choices2 = models.CharField(max_length=10, choices=[(1,2,3),(1,2,3)])
     index = models.CharField(max_length=10, db_index='bad')
     field_ = models.CharField(max_length=10)
+    nullbool = models.BooleanField(null=True)
 
 class Target(models.Model):
     tgt_safe = models.CharField(max_length=10)
@@ -190,6 +191,7 @@ invalid_models.fielderrors: "choices2": "choices" should be a sequence of two-tu
 invalid_models.fielderrors: "choices2": "choices" should be a sequence of two-tuples.
 invalid_models.fielderrors: "index": "db_index" should be either None, True or False.
 invalid_models.fielderrors: "field_": Field names cannot end with underscores, because this would lead to ambiguous queryset filters.
+invalid_models.fielderrors: "nullbool": BooleanFields cannot allow null values. Use NullBooleanField instead.
 invalid_models.clash1: Accessor for field 'foreign' clashes with field 'Target.clash1_set'. Add a related_name argument to the definition for 'foreign'.
 invalid_models.clash1: Accessor for field 'foreign' clashes with related m2m field 'Target.clash1_set'. Add a related_name argument to the definition for 'foreign'.
 invalid_models.clash1: Reverse query name for field 'foreign' clashes with field 'Target.clash1'. Add a related_name argument to the definition for 'foreign'.
diff --git a/tests/regressiontests/serializers_regress/models.py b/tests/regressiontests/serializers_regress/models.py
index e26b8df..95119d4 100644
--- a/tests/regressiontests/serializers_regress/models.py
+++ b/tests/regressiontests/serializers_regress/models.py
@@ -11,10 +11,10 @@ from django.contrib.contenttypes.models import ContentType
 from django.contrib.localflavor.us.models import USStateField, PhoneNumberField
 
 # The following classes are for testing basic data
-# marshalling, including NULL values.
+# marshalling, including NULL values, where allowed.
 
 class BooleanData(models.Model):
-    data = models.BooleanField(null=True)
+    data = models.BooleanField()
 
 class CharData(models.Model):
     data = models.CharField(max_length=30, null=True)