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:             0.1.5.0
+version:             0.1.5.1
 synopsis:            General-purpose functions by Serokell
 homepage:            https://github.com/serokell/serokell-util
 license:             MIT
diff --git a/src/Serokell/Util/Base64.hs b/src/Serokell/Util/Base64.hs
--- a/src/Serokell/Util/Base64.hs
+++ b/src/Serokell/Util/Base64.hs
@@ -13,6 +13,7 @@
 
 import           Control.Monad              ((>=>))
 import           Data.Aeson                 (FromJSON (parseJSON), ToJSON (toJSON))
+import           Data.Aeson.Types           (ToJSONKey (..), toJSONKeyText)
 import qualified Data.ByteString            as BS
 import qualified Data.ByteString.Base64     as B64
 import qualified Data.ByteString.Base64.URL as B64url
@@ -54,6 +55,9 @@
 
 instance ToJSON JsonByteString where
     toJSON = toJSON . encode . getJsonByteString
+
+instance ToJSONKey JsonByteString where
+    toJSONKey = toJSONKeyText (encode . getJsonByteString)
 
 instance FromJSON JsonByteString where
     parseJSON =