fix KeyError
diff --git a/plstackapi/core/serializers.py b/plstackapi/core/serializers.py
index db5af0f..9a1d118 100644
--- a/plstackapi/core/serializers.py
+++ b/plstackapi/core/serializers.py
@@ -52,6 +52,7 @@
     id = serializers.Field()
     site = serializers.HyperlinkedRelatedField(view_name='site-detail')
     slivers = serializers.HyperlinkedRelatedField(view_name='sliver-detail')
+    subnets = serializers.HyperlinkedRelatedField(view_name='subnet-detail')
     class Meta:
         model = Slice
         fields = ('id',