diff --git a/google-oauth2-jwt.cabal b/google-oauth2-jwt.cabal
--- a/google-oauth2-jwt.cabal
+++ b/google-oauth2-jwt.cabal
@@ -1,5 +1,5 @@
 name:                google-oauth2-jwt
-version:             0.2.1
+version:             0.2.2
 synopsis:            Get a signed JWT for Google Service Accounts
 description:         This library implements the creation of the
                      signed JWT for Google Service Accounts.
@@ -21,7 +21,7 @@
                   , base64-bytestring   >= 1.0.0    && < 1.1
                   , bytestring          >= 0.10.6   && < 0.11
                   , HsOpenSSL           >= 0.11.1.1 && < 0.12
-                  , RSA                 >= 2.1.0.3  && < 2.3
+                  , RSA                 >= 2.1.0.3  && < 2.4
                   , text                >= 1.2.2    && < 1.3
                   , unix-time           >= 0.3.6    && < 0.4
 
diff --git a/src/Network/Google/OAuth2/JWT.hs b/src/Network/Google/OAuth2/JWT.hs
--- a/src/Network/Google/OAuth2/JWT.hs
+++ b/src/Network/Google/OAuth2/JWT.hs
@@ -109,10 +109,6 @@
       (rsassa_pkcs1_v1_5_sign hashSHA256 pk $ fromStrict i)
   where
     toT = T.pack . show
-
-header :: B.ByteString
-header = toB64 "{\"alg\":\"RS256\",\"typ\":\"JWT\"}"
-
-toB64 :: T.Text -> B.ByteString
-toB64 = encode . encodeUtf8
+    toB64 = encode . encodeUtf8
+    header = toB64 "{\"alg\":\"RS256\",\"typ\":\"JWT\"}"