diff --git a/django/db/models/options.py b/django/db/models/options.py
index 6f0f406aaa..0cd52a3122 100644
--- a/django/db/models/options.py
+++ b/django/db/models/options.py
@@ -385,7 +385,7 @@ class Options(object):
                     cache[obj] = model
         for klass in get_models(include_auto_created=True, only_installed=False):
             for f in klass._meta.local_fields:
-                if f.rel and not isinstance(f.rel.to, str) and self == f.rel.to._meta:
+                if f.rel and not isinstance(f.rel.to, basestring) and self == f.rel.to._meta:
                     cache[RelatedObject(f.rel.to, klass, f)] = None
         self._related_objects_cache = cache
 
@@ -422,7 +422,7 @@ class Options(object):
                     cache[obj] = model
         for klass in get_models(only_installed=False):
             for f in klass._meta.local_many_to_many:
-                if f.rel and not isinstance(f.rel.to, str) and self == f.rel.to._meta:
+                if f.rel and not isinstance(f.rel.to, basestring) and self == f.rel.to._meta:
                     cache[RelatedObject(f.rel.to, klass, f)] = None
         if app_cache_ready():
             self._related_many_to_many_cache = cache
diff --git a/tests/modeltests/invalid_models/invalid_models/models.py b/tests/modeltests/invalid_models/invalid_models/models.py
index 45f302413d..e32ff04ea8 100644
--- a/tests/modeltests/invalid_models/invalid_models/models.py
+++ b/tests/modeltests/invalid_models/invalid_models/models.py
@@ -1,3 +1,4 @@
+#encoding=utf-8
 """
 26. Invalid models
 
@@ -218,6 +219,16 @@ class InvalidSetNull(models.Model):
 class InvalidSetDefault(models.Model):
     fk = models.ForeignKey('self', on_delete=models.SET_DEFAULT)
 
+class UnicodeForeignKeys(models.Model):
+    """Foreign keys which can translate to ascii should be OK, but fail if they're not."""
+    good = models.ForeignKey(u'FKTarget')
+    also_good = models.ManyToManyField(u'FKTarget', related_name='unicode2')
+
+    # In Python 3 this should become legal, but currently causes unicode errors
+    # when adding the errors in core/management/validation.py
+    #bad = models.ForeignKey(u'★')
+
+
 model_errors = """invalid_models.fielderrors: "charfield": CharFields require a "max_length" attribute that is a positive integer.
 invalid_models.fielderrors: "charfield2": CharFields require a "max_length" attribute that is a positive integer.
 invalid_models.fielderrors: "charfield3": CharFields require a "max_length" attribute that is a positive integer.