diff --git a/src/Utils.hs b/src/Utils.hs
index 22d1747c2..5436634d2 100644
--- a/src/Utils.hs
+++ b/src/Utils.hs
@@ -1852,7 +1852,7 @@ newtype MergeHashMap k v = MergeHashMap { unMergeHashMap :: HashMap k v }
   deriving (Show, Generic, Data)
   deriving newtype ( Eq, Ord, Hashable
                    , Functor, Foldable, NFData
-                   , ToJSON
+                   , ToJSON, FromJSON
                    )
 
 makePrisms ''MergeHashMap