diff --git a/mongoengine/fields.py b/mongoengine/fields.py
index a4640dda..b4dd456f 100644
--- a/mongoengine/fields.py
+++ b/mongoengine/fields.py
@@ -838,11 +838,10 @@ class BinaryField(BaseField):
         return Binary(value)
 
     def to_python(self, value):
-        # Returns str not unicode as this is binary data
-        return str(value)
+        return "%s" % value
 
     def validate(self, value):
-        if not isinstance(value, str):
+        if not isinstance(value, basestring):
             self.error('BinaryField only accepts string values')
 
         if self.max_bytes is not None and len(value) > self.max_bytes:
@@ -1014,7 +1013,7 @@ class FileField(BaseField):
 
     def __set__(self, instance, value):
         key = self.name
-        if (hasattr(value, 'read') and not isinstance(value, GridFSProxy)) or isinstance(value, str):
+        if (hasattr(value, 'read') and not isinstance(value, GridFSProxy)) or isinstance(value, basestring):
             # using "FileField() = file/string" notation
             grid_file = instance._data.get(self.name)
             # If a file already exists, delete it
diff --git a/mongoengine/queryset.py b/mongoengine/queryset.py
index d06e3af1..64f9441a 100644
--- a/mongoengine/queryset.py
+++ b/mongoengine/queryset.py
@@ -702,7 +702,7 @@ class QuerySet(object):
                 cleaned_fields = []
                 for field in fields:
                     append_field = True
-                    if isinstance(field, str):
+                    if isinstance(field, basestring):
                         parts.append(field)
                         append_field = False
                     else:
diff --git a/setup.cfg b/setup.cfg
index 6c5b9bae..51a18682 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -4,10 +4,10 @@ test = nosetests
 [nosetests]
 verbosity = 2
 detailed-errors = 1
-with-coverage = 1
-cover-erase = 1
-cover-html = 1
-cover-html-dir = ../htmlcov
-cover-package = mongoengine
+#with-coverage = 1
+#cover-erase = 1
+#cover-html = 1
+#cover-html-dir = ../htmlcov
+#cover-package = mongoengine
 where = tests
 #tests = test_bugfix.py