diff --git a/htest/Test/Ganeti/Rpc.hs b/htest/Test/Ganeti/Rpc.hs
index 34e8e6142fae75afbddea45f15c4a108911233b4..6e6d74f50d38b5b5bf8117a525ba02fd84909288 100644
--- a/htest/Test/Ganeti/Rpc.hs
+++ b/htest/Test/Ganeti/Rpc.hs
@@ -32,6 +32,7 @@ import Test.QuickCheck
 import Test.QuickCheck.Monadic (monadicIO, run, stop)
 
 import Control.Applicative
+import qualified Data.Map as Map
 
 import Test.Ganeti.TestHelper
 import Test.Ganeti.TestCommon
@@ -47,7 +48,8 @@ instance Arbitrary Rpc.RpcCallInstanceList where
   arbitrary = Rpc.RpcCallInstanceList <$> arbitrary
 
 instance Arbitrary Rpc.RpcCallNodeInfo where
-  arbitrary = Rpc.RpcCallNodeInfo <$> arbitrary <*> arbitrary
+  arbitrary = Rpc.RpcCallNodeInfo <$> arbitrary <*> arbitrary <*>
+                pure Map.empty
 
 -- | Monadic check that, for an offline node and a call that does not
 -- offline nodes, we get a OfflineNodeError response.
diff --git a/lib/constants.py b/lib/constants.py
index 5bc6cf36c09a324813ddd2fe5994111515de2067..49757669d89c929d99c1168f202311a08e6453b3 100644
--- a/lib/constants.py
+++ b/lib/constants.py
@@ -424,12 +424,12 @@ DTS_FILEBASED = compat.UniqueFrozenset([
 DTS_EXCL_STORAGE = frozenset([DT_PLAIN])
 
 # templates for which we don't perform checks on free space
-DTS_NO_FREE_SPACE_CHECK = frozenset([
-    DT_FILE,
-    DT_SHARED_FILE,
-    DT_RBD,
-    DT_EXT,
-    ])
+DTS_NO_FREE_SPACE_CHECK = compat.UniqueFrozenset([
+  DT_FILE,
+  DT_SHARED_FILE,
+  DT_RBD,
+  DT_EXT,
+  ])
 
 # logical disk types
 LD_LV = "lvm"