diff --git a/serokell-util.cabal b/serokell-util.cabal
--- a/serokell-util.cabal
+++ b/serokell-util.cabal
@@ -1,5 +1,5 @@
 name:                serokell-util
-version:             0.1.2.0
+version:             0.1.2.1
 synopsis:            General-purpose functions by Serokell
 homepage:            https://github.com/serokell/serokell-util
 license:             MIT
diff --git a/src/Serokell/Data/Variant/Serialization.hs b/src/Serokell/Data/Variant/Serialization.hs
--- a/src/Serokell/Data/Variant/Serialization.hs
+++ b/src/Serokell/Data/Variant/Serialization.hs
@@ -111,7 +111,7 @@
     toObject VarNone = MP.ObjectNil
     toObject (VarBool v) = MP.ObjectBool v
     toObject (VarInt v) = MP.ObjectInt $ fromIntegral v
-    toObject (VarUInt v) = MP.ObjectInt $ fromIntegral v
+    toObject (VarUInt v) = MP.ObjectWord $ fromIntegral v
     toObject (VarFloat v) = MP.ObjectDouble v
     toObject (VarBytes v) = MP.ObjectBin v
     toObject (VarString v) = MP.ObjectStr v
diff --git a/test/Test/Serokell/Data/Variant/VariantSpec.hs b/test/Test/Serokell/Data/Variant/VariantSpec.hs
--- a/test/Test/Serokell/Data/Variant/VariantSpec.hs
+++ b/test/Test/Serokell/Data/Variant/VariantSpec.hs
@@ -80,12 +80,6 @@
                               m' = HM.fromList $ zip ks vs
                           in S.VarMap m'
 msgPkFixer (S.VarList l) = S.VarList $ V.map msgPkFixer l
-msgPkFixer v@(S.VarInt i) =
-    if i < 0 then v
-             else (S.VarUInt $ fromIntegral i)
-msgPkFixer v@(S.VarUInt i) =
-    if i >= 0 then v
-             else (S.VarInt $ fromIntegral i)
 msgPkFixer v = v
 
 msgPkMid :: S.Variant -> S.Variant