diff --git a/perf.cabal b/perf.cabal
--- a/perf.cabal
+++ b/perf.cabal
@@ -1,6 +1,6 @@
 cabal-version:      2.4
 name:               perf
-version:            0.10.2
+version:            0.10.3
 synopsis:           Low-level run time measurement.
 description:
   A set of tools to measure performance of Haskell programs.
@@ -20,16 +20,19 @@
 extra-source-files: ChangeLog.md
 
 source-repository head
-  type:     git
+  type: git
   location: https://github.com/tonyday567/perf
 
 common ghc-options-stanza
   ghc-options:
-    -Wall -Wcompat -Wincomplete-record-updates
-    -Wincomplete-uni-patterns -Wredundant-constraints
+    -Wall
+    -Wcompat
+    -Wincomplete-record-updates
+    -Wincomplete-uni-patterns
+    -Wredundant-constraints
 
 library
-  import:             ghc-options-stanza
+  import: ghc-options-stanza
   exposed-modules:
     Perf
     Perf.Algos
@@ -43,18 +46,18 @@
 
   hs-source-dirs:     src
   build-depends:
-    , base                  >=4.7    && <5
-    , containers            ^>=0.6
-    , deepseq               >=1.4.4  && <1.5
-    , formatn               ^>=0.2.1
-    , mtl                   >=2.2.2 && <2.4
-    , numhask-space         ^>=0.10
-    , optparse-applicative  ^>=0.17
-    , rdtsc                 ^>=1.3
-    , recursion-schemes     ^>=5.2.2
-    , text                  >=1.2 && <2.1
-    , time                  >=1.9 && <1.13
-    , vector                >=0.12.3 && <0.14
+    base >=4.7 && <5,
+    containers ^>=0.6,
+    deepseq >=1.4.4 && <1.5,
+    formatn >=0.2.1 && < 0.4,
+    mtl >=2.2.2 && <2.4,
+    numhask-space ^>=0.10,
+    optparse-applicative ^>=0.17,
+    rdtsc ^>=1.3,
+    recursion-schemes ^>=5.2.2,
+    text >=1.2 && <2.1,
+    time >=1.9 && <1.13,
+    vector >=0.12.3 && <0.14,
 
   default-language:   Haskell2010
   default-extensions:
@@ -65,24 +68,15 @@
   main-is:          explore.hs
   hs-source-dirs:   app
   build-depends:
-    , base                  >=4.7   && <5
-    , containers            ^>=0.6
-    , deepseq               >=1.4.4 && <1.5
-    , formatn               >=0.2 && <0.3
-    , gauge                 ^>=0.2.5
-    , mtl                   >=2.2.2 && <2.4
-    , optparse-applicative  ^>=0.17
-    , perf
-    , text                  >=1.2 && <2.1
+    base >=4.7 && <5,
+    containers ^>=0.6,
+    deepseq >=1.4.4 && <1.5,
+    formatn >=0.2.1 && <0.4,
+    gauge ^>=0.2.5,
+    mtl >=2.2.2 && <2.4,
+    optparse-applicative ^>=0.17,
+    perf,
+    text >=1.2 && <2.1,
 
   default-language: Haskell2010
   ghc-options:      -O2
-
-test-suite doctests
-  type:             exitcode-stdio-1.0
-  main-is:          doctests.hs
-  hs-source-dirs:   test
-  default-language: Haskell2010
-  build-depends:
-    , base
-    , QuickCheck
diff --git a/src/Perf.hs b/src/Perf.hs
--- a/src/Perf.hs
+++ b/src/Perf.hs
@@ -1,7 +1,3 @@
-{-# LANGUAGE GADTs #-}
-{-# LANGUAGE MultiParamTypeClasses #-}
-{-# LANGUAGE RankNTypes #-}
-{-# LANGUAGE RebindableSyntax #-}
 {-# OPTIONS_GHC -Wall #-}
 
 -- | == Introduction
@@ -17,9 +13,9 @@
 -- - functionality to determine performance order, in 'Perf.BigO'
 --
 -- Usage examples can be found in app/perf-explore.hs and the project's readme.org.
---
 module Perf
   ( -- * re-exports
+
     -- | Various (fast loop) algorithms that have been used for testing perf functionality.
     module Perf.Algos,
     -- | Low-level time performance 'Measure's counting 'Cycles'
diff --git a/src/Perf/BigO.hs b/src/Perf/BigO.hs
--- a/src/Perf/BigO.hs
+++ b/src/Perf/BigO.hs
@@ -1,7 +1,5 @@
 {-# LANGUAGE DeriveFunctor #-}
 {-# LANGUAGE DeriveGeneric #-}
-{-# LANGUAGE FlexibleContexts #-}
-{-# LANGUAGE NegativeLiterals #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# OPTIONS_GHC -Wall #-}
 
diff --git a/src/Perf/Space.hs b/src/Perf/Space.hs
--- a/src/Perf/Space.hs
+++ b/src/Perf/Space.hs
@@ -3,7 +3,6 @@
 {-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE RankNTypes #-}
-{-# LANGUAGE RebindableSyntax #-}
 {-# OPTIONS_GHC -Wall #-}
 
 -- | Space performance measurement.
@@ -13,12 +12,11 @@
     spaceLabels,
     space,
     allocation,
-    Bytes(..),
+    Bytes (..),
   )
 where
 
 import Control.Monad.State.Lazy
-import Data.String
 import Data.Text (Text)
 import Data.Word
 import GHC.Stats
@@ -30,7 +28,7 @@
 data SpaceStats = SpaceStats {allocatedBytes :: Word64, gcollects :: Word32, maxLiveBytes :: Word64, gcLiveBytes :: Word64, maxMem :: Word64} deriving (Read, Show, Eq)
 
 -- | Convert 'SpaceStats' to a list of numbers.
-ssToList :: Num a => SpaceStats -> [a]
+ssToList :: (Num a) => SpaceStats -> [a]
 ssToList (SpaceStats x1 x2 x3 x4 x5) = [fromIntegral x1, fromIntegral x2, fromIntegral x3, fromIntegral x4, fromIntegral x5]
 
 instance Semigroup SpaceStats where
diff --git a/src/Perf/Time.hs b/src/Perf/Time.hs
--- a/src/Perf/Time.hs
+++ b/src/Perf/Time.hs
@@ -1,7 +1,5 @@
 {-# LANGUAGE BangPatterns #-}
-{-# LANGUAGE DerivingVia #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
-{-# LANGUAGE RebindableSyntax #-}
 {-# LANGUAGE ViewPatterns #-}
 {-# OPTIONS_GHC -Wall #-}
 {-# OPTIONS_GHC -fno-warn-orphans #-}
diff --git a/src/Perf/Types.hs b/src/Perf/Types.hs
--- a/src/Perf/Types.hs
+++ b/src/Perf/Types.hs
@@ -1,11 +1,10 @@
 {-# LANGUAGE BangPatterns #-}
 {-# LANGUAGE DeriveFunctor #-}
-{-# LANGUAGE GADTs #-}
+{-# LANGUAGE ExistentialQuantification #-}
 {-# LANGUAGE GeneralizedNewtypeDeriving #-}
 {-# LANGUAGE MultiParamTypeClasses #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE RankNTypes #-}
-{-# LANGUAGE RebindableSyntax #-}
 {-# LANGUAGE TupleSections #-}
 {-# OPTIONS_GHC -Wall #-}
 
@@ -48,7 +47,6 @@
 import Data.Bifunctor
 import Data.Functor.Identity
 import qualified Data.Map.Strict as Map
-import Data.String
 import Data.Text (Text)
 import Prelude
 
@@ -105,7 +103,7 @@
 {-# INLINEABLE toMeasureN #-}
 
 -- | A single step measurement.
-step :: Monad m => m i -> (i -> m t) -> (a -> b) -> a -> m (t, b)
+step :: (Monad m) => m i -> (i -> m t) -> (a -> b) -> a -> m (t, b)
 step pre' post' !f !a = do
   !p <- pre'
   !b <- pure $! f a
@@ -114,7 +112,7 @@
 {-# INLINEABLE step #-}
 
 -- | A single step measurement.
-stepM :: Monad m => m i -> (i -> m t) -> m a -> m (t, a)
+stepM :: (Monad m) => m i -> (i -> m t) -> m a -> m (t, a)
 stepM pre' post' a = do
   !p <- pre'
   !ma <- a
@@ -123,13 +121,13 @@
 {-# INLINEABLE stepM #-}
 
 -- | Multiple measurement
-multi :: Monad m => ((a -> b) -> a -> m (t, b)) -> Int -> (a -> b) -> a -> m ([t], b)
+multi :: (Monad m) => ((a -> b) -> a -> m (t, b)) -> Int -> (a -> b) -> a -> m ([t], b)
 multi action n !f !a =
   fmap (\xs -> (fmap fst xs, snd (head xs))) (replicateM n (action f a))
 {-# INLINEABLE multi #-}
 
 -- | Multiple measurements
-multiM :: Monad m => (m a -> m (t, a)) -> Int -> m a -> m ([t], a)
+multiM :: (Monad m) => (m a -> m (t, a)) -> Int -> m a -> m ([t], a)
 multiM action n a =
   fmap (\xs -> (fmap fst xs, snd (head xs))) (replicateM n (action a))
 {-# INLINEABLE multiM #-}
@@ -214,12 +212,12 @@
 
 -- | Consume the PerfT layer and return the original monadic result.
 -- Fingers crossed, PerfT structure should be completely compiled away.
-evalPerfT :: Monad m => Measure m t -> PerfT m t a -> m a
+evalPerfT :: (Monad m) => Measure m t -> PerfT m t a -> m a
 evalPerfT m p = fmap fst <$> flip runStateT (m, Map.empty) $ measurePerf p
 {-# INLINEABLE evalPerfT #-}
 
 -- | Consume a PerfT layer and return the measurement.
-execPerfT :: Monad m => Measure m t -> PerfT m t a -> m (Map.Map Text t)
+execPerfT :: (Monad m) => Measure m t -> PerfT m t a -> m (Map.Map Text t)
 execPerfT m p = fmap snd <$> flip execStateT (m, Map.empty) $ measurePerf p
 {-# INLINEABLE execPerfT #-}
 
diff --git a/test/doctests.hs b/test/doctests.hs
deleted file mode 100644
--- a/test/doctests.hs
+++ /dev/null
@@ -1,8 +0,0 @@
-module Main where
-
-main :: IO ()
-main = do
-  putStrLn "This test-suite exists only to add dependencies"
-  putStrLn "To run doctests: "
-  putStrLn "    cabal build all --enable-tests"
-  putStrLn "    cabal-docspec"