diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Changelog for `wai-rate-limit`
 
+## 0.3
+
+- Use the `Second` type from `Data.Time.Units` to more accurately represent the expected arguments for the rate-limiting strategies.
+
 ## 0.2
 
 - Change how errors are handled by `Backend`s to use exceptions
diff --git a/src/Network/Wai/RateLimit/Strategy.hs b/src/Network/Wai/RateLimit/Strategy.hs
--- a/src/Network/Wai/RateLimit/Strategy.hs
+++ b/src/Network/Wai/RateLimit/Strategy.hs
@@ -5,6 +5,7 @@
 -- file in the root directory of this source tree.                            --
 --------------------------------------------------------------------------------
 
+-- | Exports functions which implement rate-limiting strategies.
 module Network.Wai.RateLimit.Strategy (
     Strategy(..),
     fixedWindow,
@@ -15,6 +16,8 @@
 
 import Control.Monad
 
+import Data.Time.Units
+
 import Network.Wai
 import Network.Wai.RateLimit.Backend
 
@@ -28,14 +31,17 @@
     strategyOnRequest :: Request -> IO Bool
 }
 
--- | 'windowStrategy'
+-- | `windowStrategy` implements a general window-based rate limiting strategy.
 windowStrategy
-    :: Backend key
-    -> Integer
-    -> Integer
-    -> (Request -> IO key)
-    -> (Integer -> Bool)
-    -> Request
+    :: Backend key -- ^ The storage backend to use.
+    -> Second -- ^ The number of seconds after which recorded usage expires.
+    -> Integer -- ^ How much capacity each key should have.
+    -> (Request -> IO key) -- ^ A function which computes a key for the
+                           -- request.
+    -> (Integer -> Bool) -- ^ A predicate which determines whether the expiry
+                         -- timer should be reset.
+    -> Request -- ^ The request to apply the stragey to, used for deriving
+               -- the key.
     -> IO Bool
 windowStrategy MkBackend{..} seconds capacity getKey cond req = do
     -- get a key to identify the usage bucket for the request: this is
@@ -50,7 +56,7 @@
     -- acceptable limit and, if so, add to the expiry timer
     if used <= capacity
     then do
-        when (cond used) $ void $ backendExpireIn key seconds
+        when (cond used) $ void $ backendExpireIn key (toInteger seconds)
         pure True
     else pure False
 
@@ -58,7 +64,7 @@
 -- of requests made by a client to @limit@ within a window of @seconds@.
 fixedWindow
     :: Backend key
-    -> Integer
+    -> Second
     -> Integer
     -> (Request -> IO key)
     -> Strategy
@@ -76,7 +82,7 @@
 -- been exceeded.
 slidingWindow
     :: Backend key
-    -> Integer
+    -> Second
     -> Integer
     -> (Request -> IO key)
     -> Strategy
diff --git a/wai-rate-limit.cabal b/wai-rate-limit.cabal
--- a/wai-rate-limit.cabal
+++ b/wai-rate-limit.cabal
@@ -5,7 +5,7 @@
 -- see: https://github.com/sol/hpack
 
 name:           wai-rate-limit
-version:        0.2.0.0
+version:        0.3.0.0
 synopsis:       Rate limiting as WAI middleware
 description:    A Haskell library which implements rate limiting as WAI middleware
 category:       Security
@@ -41,5 +41,6 @@
   build-depends:
       base >=4.8 && <5
     , http-types <1
+    , time-units ==1.*
     , wai >=3.0 && <4
   default-language: Haskell2010