diff --git a/primer-service/src/Primer/OpenAPI.hs b/primer-service/src/Primer/OpenAPI.hs
index 58c001a67..26359c723 100644
--- a/primer-service/src/Primer/OpenAPI.hs
+++ b/primer-service/src/Primer/OpenAPI.hs
@@ -1,3 +1,4 @@
+{-# LANGUAGE StandaloneDeriving #-}
 {-# OPTIONS_GHC -fno-warn-orphans #-}
 
 module Primer.OpenAPI (
@@ -6,9 +7,10 @@ module Primer.OpenAPI (
 ) where
 
 import Data.OpenApi (ToSchema)
+import Data.Text (Text)
 import Primer.API (APIDef, APIProg, Tree)
 import Primer.App (InitialApp)
-import Primer.Core (ID)
+import Primer.Core (ID (..))
 import Primer.Database (Session, SessionName)
 import Primer.Name (Name)
 
@@ -22,8 +24,14 @@ import Primer.Name (Name)
 instance ToSchema SessionName
 instance ToSchema Session
 instance ToSchema InitialApp
-instance ToSchema ID
-instance ToSchema Name
+
+-- We need to GND the ID instance to matche its To/FromJSON instances
+deriving newtype instance ToSchema ID
+
+-- We can't GND derive for Name as it is an opaque class
+-- But the JSON instance is done by GND, so we must match here...
+-- This instance works because the parameter has a phantom role!
+deriving via Text instance (ToSchema Name)
 instance ToSchema Tree
 instance ToSchema APIDef
 instance ToSchema APIProg
diff --git a/primer/src/Primer/API.hs b/primer/src/Primer/API.hs
index 18987f76d..fb464a069 100644
--- a/primer/src/Primer/API.hs
+++ b/primer/src/Primer/API.hs
@@ -277,7 +277,7 @@ getProgram sid = withSession' sid $ QueryApp $ viewProg . handleGetProgramReques
 -- just enough information to render nicely.
 -- (NB: currently this is just a first draft, and is expected to evolve.)
 data Tree = Tree
-  { nodeId :: ID -- REVIEW: here, and in APIDef we maybe want a raw Int, as IDs serialise as '{unID: 5}'
+  { nodeId :: ID
   , label :: Text
   , children :: [Tree]
   }
diff --git a/primer/src/Primer/Core.hs b/primer/src/Primer/Core.hs
index 6e7859dcc..40e8f0a39 100644
--- a/primer/src/Primer/Core.hs
+++ b/primer/src/Primer/Core.hs
@@ -64,7 +64,7 @@ newtype ID = ID {unID :: Int}
   -- The Ord and Enum instances are useful for tests but we may remove them in
   -- future, so don't use them in app code.
   deriving newtype (Show, Num, Ord, Enum)
-  deriving (FromJSON, ToJSON) via VJSON ID
+  deriving newtype (FromJSON, ToJSON)
 
 instance ToJSONKey ID
 
diff --git a/primer/src/Primer/Name.hs b/primer/src/Primer/Name.hs
index 1c2ec2804..654a73af5 100644
--- a/primer/src/Primer/Name.hs
+++ b/primer/src/Primer/Name.hs
@@ -23,7 +23,7 @@ import Primer.JSON
 newtype Name = Name {unName :: Text}
   deriving (Eq, Ord, Generic, Data)
   deriving newtype (Show, IsString)
-  deriving (FromJSON, ToJSON) via VJSON Name
+  deriving newtype (FromJSON, ToJSON)
 
 -- | Construct a name from a Text. This is called unsafe because there are no
 -- guarantees about whether the name refers to anything that is in scope.