diff --git a/django/db/models/sql/query.py b/django/db/models/sql/query.py
index 9f303fa015..c1013ce99f 100644
--- a/django/db/models/sql/query.py
+++ b/django/db/models/sql/query.py
@@ -634,10 +634,13 @@ class Query(object):
         self.rev_join_map[alias] = t_ident
         return alias
 
-    def fill_related_selections(self, opts=None, root_alias=None, cur_depth=0,
+    def fill_related_selections(self, opts=None, root_alias=None, cur_depth=1,
             used=None):
         """
-        Fill in the information needed for a select_related query.
+        Fill in the information needed for a select_related query. The current
+        "depth" is measured as the number of connections away from the root
+        model (cur_depth == 1 means we are looking at models with direct
+        connections to the root model).
         """
         if self.max_depth and cur_depth > self.max_depth:
             # We've recursed too deeply; bail out.
diff --git a/tests/modeltests/select_related/models.py b/tests/modeltests/select_related/models.py
index 78ba0ba764..a52cc986a4 100644
--- a/tests/modeltests/select_related/models.py
+++ b/tests/modeltests/select_related/models.py
@@ -147,6 +147,10 @@ __test__ = {'API_TESTS':"""
 >>> len(db.connection.queries)
 5
 
+>>> s = Species.objects.all().select_related(depth=1).extra(select={'a': 'select_related_species.id + 10'})[0]
+>>> s.id + 10 == s.a
+True
+
 # Reset DEBUG to where we found it.
 >>> settings.DEBUG = False
 """}