diff --git a/rest_framework/serializers.py b/rest_framework/serializers.py
index ecff2c524..7707de7a7 100644
--- a/rest_framework/serializers.py
+++ b/rest_framework/serializers.py
@@ -649,8 +649,14 @@ class ModelSerializer(Serializer):
         # Add the `read_only` flag to any fields that have bee specified
         # in the `read_only_fields` option
         for field_name in self.opts.read_only_fields:
+            assert field_name not in self.base_fields.keys(), \
+                "field '%s' on serializer '%s' specfied in " \
+                "`read_only_fields`, but also added " \
+                "as an explict field.  Remove it from `read_only_fields`." % \
+                (field_name, self.__class__.__name__)
             assert field_name in ret, \
-                "read_only_fields on '%s' included invalid item '%s'" % \
+                "Noexistant field '%s' specified in `read_only_fields` " \
+                "on serializer '%s'." % \
                 (self.__class__.__name__, field_name)
             ret[field_name].read_only = True
 
diff --git a/rest_framework/tests/serializer.py b/rest_framework/tests/serializer.py
index 84e1ee4e0..db3881f9a 100644
--- a/rest_framework/tests/serializer.py
+++ b/rest_framework/tests/serializer.py
@@ -78,6 +78,18 @@ class PersonSerializer(serializers.ModelSerializer):
         read_only_fields = ('age',)
 
 
+class PersonSerializerInvalidReadOnly(serializers.ModelSerializer):
+    """
+    Testing for #652.
+    """
+    info = serializers.Field(source='info')
+
+    class Meta:
+        model = Person
+        fields = ('name', 'age', 'info')
+        read_only_fields = ('age', 'info')
+
+
 class AlbumsSerializer(serializers.ModelSerializer):
 
     class Meta:
@@ -189,6 +201,12 @@ class BasicTests(TestCase):
         # Assert age is unchanged (35)
         self.assertEqual(instance.age, self.person_data['age'])
 
+    def test_invalid_read_only_fields(self):
+        """
+        Regression test for #652.
+        """
+        self.assertRaises(AssertionError, PersonSerializerInvalidReadOnly, [])
+
 
 class DictStyleSerializer(serializers.Serializer):
     """