diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+# monad-time-0.4.0.0 (2022-07-05)
+* Added `monotonicTime` to `MonadTime`
+* Removed the `MonadTime` instance for `ReaderT UTCTime`
+
 # monad-time-0.3.1.0 (2018-04-09)
 * Restored compatibility with GHC versions < 7.10
   ([#4](https://github.com/scrive/monad-time/issues/4)).
diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -1,4 +1,3 @@
 # monad-time [![Hackage version](https://img.shields.io/hackage/v/monad-time.svg?label=Hackage)](https://hackage.haskell.org/package/monad-time) [![Build Status](https://secure.travis-ci.org/scrive/monad-time.svg?branch=master)](http://travis-ci.org/scrive/monad-time)
 
-A `MonadTime` type class for monads which carry the notion of the
-current time.
+`MonadTime` type class for monads which make it possible to measure time.
diff --git a/monad-time.cabal b/monad-time.cabal
--- a/monad-time.cabal
+++ b/monad-time.cabal
@@ -1,5 +1,5 @@
 name:                monad-time
-version:             0.3.1.0
+version:             0.4.0.0
 synopsis:            Type class for monads which carry
                      the notion of the current time.
 description:         'MonadTime' type class for monads
@@ -16,8 +16,7 @@
 build-type:          Simple
 cabal-version:       >=1.10
 extra-source-files:  README.md CHANGELOG.md
-tested-with:         GHC == 7.4.2, GHC == 7.6.3, GHC == 7.8.4, GHC == 7.10.3,
-                     GHC == 8.0.2, GHC == 8.2.2, GHC == 8.4.1
+tested-with:         GHC == 8.8.4, GHC == 8.10.7, GHC == 9.0.2, GHC == 9.2.3
 
 source-repository head
   type:     git
@@ -26,7 +25,7 @@
 library
   exposed-modules:   Control.Monad.Time
 
-  build-depends:     base < 5,
+  build-depends:     base >=4.13 && < 5,
                      mtl,
                      time
 
diff --git a/src/Control/Monad/Time.hs b/src/Control/Monad/Time.hs
--- a/src/Control/Monad/Time.hs
+++ b/src/Control/Monad/Time.hs
@@ -7,23 +7,18 @@
 module Control.Monad.Time (MonadTime(..)) where
 
 import Control.Monad.Trans
-import Control.Monad.Reader (ReaderT, ask)
 import Data.Time
+import GHC.Clock (getMonotonicTime)
 
--- | Class of monads which carry the notion of the current time.
+-- | Class of monads which make it possible to measure time.
 class Monad m => MonadTime m where
   currentTime :: m UTCTime
+  monotonicTime :: m Double
 
 -- | Base instance for IO.
 instance MonadTime IO where
   currentTime = getCurrentTime
-
--- | This is @ReaderT UTCTime@ on purpose, to avoid breaking
--- downstream.
---
--- @since 0.3.0.0
-instance {-# OVERLAPPING #-} Monad m => MonadTime (ReaderT UTCTime m) where
-  currentTime = ask
+  monotonicTime = getMonotonicTime
 
 -- | Generic, overlapping instance.
 instance {-# OVERLAPPABLE #-} (
@@ -32,3 +27,4 @@
   , Monad (t m)
   ) => MonadTime (t m) where
     currentTime = lift currentTime
+    monotonicTime = lift monotonicTime
diff --git a/test/Main.hs b/test/Main.hs
--- a/test/Main.hs
+++ b/test/Main.hs
@@ -12,6 +12,7 @@
   -- Test that generic MonadTrans instance works.
   runReaderT currentTime 'x' >>= print
   evalStateT (runReaderT currentTime 'x') 'y' >>= print
-  -- Test that ReaderT UTCTime instance works
-  now <- getCurrentTime
-  runReaderT currentTime now >>= print
+
+  monotonicTime >>= print
+  runReaderT monotonicTime 'x' >>= print
+  evalStateT (runReaderT monotonicTime 'x') 'y' >>= print