diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,10 @@
 # Revision history for fixed-timestep
 
+## 0.2.0.1 -- 2019-03-25
+
+* Improve docs
+  * Clarify that frequencies are given in units of Hertz.
+
 ## 0.2.0.0 -- 2019-03-25
 
 * Rename `Time.Flick.secnd` to `Time.Flick.oneSecond`
diff --git a/fixed-timestep.cabal b/fixed-timestep.cabal
--- a/fixed-timestep.cabal
+++ b/fixed-timestep.cabal
@@ -4,7 +4,7 @@
 -- http://haskell.org/cabal/users-guide/
 
 name:                fixed-timestep
-version:             0.2.0.0
+version:             0.2.0.1
 synopsis:            Pure Haskell library to repeat an action at a specific frequency.
 description:         Repeat IO actions at a specific frequency, using
                      flicks (1/705600000 of a second) for timekeeping.
diff --git a/lib/Time/Repeatedly.hs b/lib/Time/Repeatedly.hs
--- a/lib/Time/Repeatedly.hs
+++ b/lib/Time/Repeatedly.hs
@@ -1,5 +1,8 @@
 -- | Utilities for repeatedly running @'IO'@ actions
 -- at a specific frequency.
+-- 
+-- Frequencies are in Hertz; for example, @'repeatedly' 20 act@
+-- will run @act@ 20 times per second.
 module Time.Repeatedly
   ( -- * Repeating actions
     repeatedly
@@ -36,31 +39,31 @@
   , tscClockType :: Clock
   } deriving Eq
 
--- | Run an action repeatedly at the specified frequency.
+-- | Run an action repeatedly at the specified frequency (in Hertz).
 -- Uses the 'Monotonic' clock for timing.
 repeatedly :: Rational -> IO a -> IO void
 repeatedly freq = repeatedly' freq Monotonic
 
--- | Run an action repeatedly at the specified frequency,
+-- | Run an action repeatedly at the specified frequency (in Hertz),
 -- using the given clock type.
 repeatedly' :: Rational -> Clock -> IO a -> IO void
 repeatedly' freq clockTy act = do
   clock <- newClock freq clockTy
   loopUsing clock act
 
--- | Run an action repeatedly at the specified frequency, in a separate thread.
+-- | Run an action repeatedly at the specified frequency (in Hertz), in a separate thread.
 -- Uses the 'Monotonic' clock for timing.
 asyncRepeatedly :: Rational -> IO a -> IO (Async void)
 asyncRepeatedly freq = asyncRepeatedly' freq Monotonic
 
--- | Run an action repeatedly at the specified frequency, in a separate thread,
+-- | Run an action repeatedly at the specified frequency (in Hertz), in a separate thread,
 -- using the given clock type.
 asyncRepeatedly' :: Rational -> Clock -> IO a -> IO (Async void)
 asyncRepeatedly' freq clockTy act = do
   clock <- newClock freq clockTy
   async (loopUsing clock act)
 
--- | Initialise a new clock structure for the given frequency and using
+-- | Initialise a new clock structure for the given frequency (in Hertz) and using
 -- the given clock type.
 newClock :: Rational -> Clock -> IO TimeStepClock
 newClock freq clockTy = do