diff --git a/perf.cabal b/perf.cabal
--- a/perf.cabal
+++ b/perf.cabal
@@ -1,5 +1,6 @@
+cabal-version: 3.0
 name:           perf
-version:        0.5.0.0
+version:        0.6.0
 synopsis:       Low-level run time measurement.
 description:     A set of tools to accurately measure time performance of Haskell programs.
                 perf aims to be lightweight by having minimal dependencies on standard libraries.
@@ -10,12 +11,11 @@
 author:         Tony Day, Marco Zocca
 maintainer:     tonyday567@gmail.com
 copyright:      Tony Day
-license:        BSD3
+license:        BSD-3-Clause
 license-file:   LICENSE
 build-type:     Simple
 extra-source-files:
     CHANGELOG.md
-cabal-version: 2.0
 
 source-repository head
   type: git
diff --git a/src/Perf.hs b/src/Perf.hs
--- a/src/Perf.hs
+++ b/src/Perf.hs
@@ -61,7 +61,6 @@
 import Control.Monad.Trans.Class (lift)
 import Control.Monad.Trans.State (StateT(..), evalStateT, runStateT, execStateT, get, put )
 import Data.Functor.Identity
-import Data.Monoid ((<>))
 import Perf.Cycle
 import Perf.Measure
 import qualified Data.Map as Map