diff --git a/asap.cabal b/asap.cabal
--- a/asap.cabal
+++ b/asap.cabal
@@ -1,5 +1,5 @@
 name:                asap
-version:             0.0.3
+version:             0.0.4
 synopsis:            Atlassian Service Authentication Protocol
 description:         Atlassian Service Authentication Protocol.
 homepage:            https://bitbucket.org/atlassian-marketplace/haskell-asap
@@ -27,7 +27,7 @@
                      , text                 >= 1.2 && < 1.3
                      , time                 >= 1.8 && < 1.9
                      , semigroups           >= 0.18 && < 0.19
-                     , lens                 >= 4.16 && < 4.18
+                     , lens                 >= 4.15 && < 4.18
                      , uuid                 >= 1.3 && < 1.4
 
 test-suite asap-tests
diff --git a/lib/Web/JWT/ASAP.hs b/lib/Web/JWT/ASAP.hs
--- a/lib/Web/JWT/ASAP.hs
+++ b/lib/Web/JWT/ASAP.hs
@@ -26,6 +26,7 @@
 import           Data.ByteString.Char8 as BS (unlines)
 import           Data.ByteString.Lens  (packedChars)
 import           Data.IORef            (newIORef, readIORef, writeIORef)
+import           Data.Semigroup
 import           Data.String           (fromString)
 import qualified Data.Text             as T
 import           Data.Time             (NominalDiffTime)