diff --git a/src/Renderer/JSON.hs b/src/Renderer/JSON.hs
index a4b18f6b0..ea9b73401 100644
--- a/src/Renderer/JSON.hs
+++ b/src/Renderer/JSON.hs
@@ -36,8 +36,8 @@ json diff sources = toLazyByteString . fromEncoding . pairs $
 newtype NumberedLine a = NumberedLine (Int, Line a)
 
 instance ToJSON a => ToJSON (NumberedLine a) where
-  toJSON (NumberedLine (n, a)) = object [ "number" .= n, "terms" .= unLine a ]
-  toEncoding (NumberedLine (n, a)) = pairs ("number" .= n <> "terms" .= unLine a)
+  toJSON (NumberedLine (n, a)) = object (lineFields n a)
+  toEncoding (NumberedLine (n, a)) = pairs $ mconcat (lineFields n a)
 instance ToJSON Category where
   toJSON (Other s) = String $ T.pack s
   toJSON s = String . T.pack $ show s
@@ -59,6 +59,9 @@ instance ToJSON (Term leaf Info) where
   toJSON (info :< syntax) = object (termFields info syntax)
   toEncoding (info :< syntax) = pairs $ mconcat (termFields info syntax)
 
+lineFields :: (ToJSON a, KeyValue kv) => Int -> Line a -> [kv]
+lineFields n line = [ "number" .= n, "terms" .= unLine line ]
+
 termFields :: (ToJSON recur, KeyValue kv) => Info -> Syntax leaf recur -> [kv]
 termFields (Info range categories) syntax = "range" .= range : "categories" .= categories : case syntax of
   Leaf _ -> []