diff --git a/rest_framework/relations.py b/rest_framework/relations.py
index 2c88071fd..1ca1a03ec 100644
--- a/rest_framework/relations.py
+++ b/rest_framework/relations.py
@@ -491,11 +491,11 @@ class ManyRelatedField(Field):
             self.fail('not_a_list', input_type=type(data).__name__)
         if not self.allow_empty and len(data) == 0:
             self.fail('empty')
-            
+
         if isinstance(self.child_relation, PrimaryKeyRelatedField):
             values = list(self.child_relation.get_queryset().filter(pk__in=data))
             missing_primary_keys = set(v.pk for v in values) - set(data)
-        
+
             if missing_primary_keys:
                 self.fail('missing_ids', ids_not_found=list(missing_primary_keys))
         else: