diff --git a/model_utils/managers.py b/model_utils/managers.py
index c15bec7..132d84a 100644
--- a/model_utils/managers.py
+++ b/model_utils/managers.py
@@ -101,7 +101,7 @@ class PassThroughManager(models.Manager):
 
     """
     # pickling causes recursion errors
-    _deny_methods = ['__getstate__', '__setstate__']
+    _deny_methods = ['__getstate__', '__setstate__', '_db']
 
     def __init__(self, queryset_cls=None):
         self._queryset_cls = queryset_cls
@@ -114,7 +114,10 @@ class PassThroughManager(models.Manager):
 
     def get_query_set(self):
         if self._queryset_cls is not None:
-            return self._queryset_cls(self.model, using=self._db)
+            kargs = {'model': self.model}
+            if hasattr(self, '_db'):
+                kargs['using'] = self._db
+            return self._queryset_cls(**kargs)
         return super(PassThroughManager, self).get_query_set()
 
 
diff --git a/model_utils/tests/models.py b/model_utils/tests/models.py
index 6adcb0e..2a72847 100644
--- a/model_utils/tests/models.py
+++ b/model_utils/tests/models.py
@@ -145,7 +145,7 @@ class DudeQuerySet(models.query.QuerySet):
 
 class AbidingManager(PassThroughManager):
     def get_query_set(self):
-        return DudeQuerySet(self.model, using=self._db).abiding()
+        return DudeQuerySet(self.model).abiding()
 
     def get_stats(self):
         return {