diff --git a/Web/PathPieces.hs b/Web/PathPieces.hs
--- a/Web/PathPieces.hs
+++ b/Web/PathPieces.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE FlexibleInstances, TypeSynonymInstances  #-}
+{-# LANGUAGE FlexibleInstances, TypeSynonymInstances, OverloadedStrings #-}
 module Web.PathPieces
     ( PathPiece (..)
     , PathMultiPiece (..)
@@ -14,6 +14,7 @@
 import qualified Data.Text.Lazy as L
 import qualified Data.Text.Read
 import Data.Time (Day)
+import Control.Exception (assert)
 
 class PathPiece s where
     fromPathPiece :: S.Text -> Maybe s
@@ -34,22 +35,29 @@
 instance PathPiece Integer where
     fromPathPiece s =
         case Data.Text.Read.signed Data.Text.Read.decimal s of
-            Right (i, _) -> Just i
-            Left _ -> Nothing
+            Right (i, "") -> Just i
+            _ -> Nothing
     toPathPiece = S.pack . show
 
 instance PathPiece Int where
     fromPathPiece s =
         case Data.Text.Read.signed Data.Text.Read.decimal s of
-            Right (i, _) -> Just i
-            Left _ -> Nothing
+            Right (i, "") -> Just i
+            _ -> Nothing
     toPathPiece = S.pack . show
 
+instance PathPiece Bool where
+    fromPathPiece t =
+        case filter (null . snd) $ reads $ S.unpack t of
+            (a, s):_ -> assert (null s) (Just a)
+            _        -> Nothing
+    toPathPiece = S.pack . show
+
 instance PathPiece Int64 where
     fromPathPiece s =
         case Data.Text.Read.signed Data.Text.Read.decimal s of
-            Right (i, _) -> Just i
-            Left _ -> Nothing
+            Right (i, "") -> Just i
+            _ -> Nothing
     toPathPiece = S.pack . show
 
 instance PathPiece Day where
@@ -58,6 +66,16 @@
             [(a,"")] -> Just a
             _ -> Nothing
     toPathPiece = S.pack . show
+
+instance (PathPiece a) => PathPiece (Maybe a) where
+    fromPathPiece s = case S.stripPrefix "Just " s of
+        Just r -> Just `fmap` fromPathPiece r
+        _ -> case s of
+            "Nothing" -> Just Nothing
+            _ -> Nothing
+    toPathPiece m = case m of
+        Just s -> "Just " `S.append` toPathPiece s
+        _ -> "Nothing"
 
 class PathMultiPiece s where
     fromPathMultiPiece :: [S.Text] -> Maybe s
diff --git a/path-pieces.cabal b/path-pieces.cabal
--- a/path-pieces.cabal
+++ b/path-pieces.cabal
@@ -1,5 +1,5 @@
 name:            path-pieces
-version:         0.1.3.1
+version:         0.1.4
 license:         BSD3
 license-file:    LICENSE
 author:          Michael Snoyman <michael@snoyman.com>
diff --git a/test/main.hs b/test/main.hs
--- a/test/main.hs
+++ b/test/main.hs
@@ -27,21 +27,31 @@
         Nothing -> null p
         Just pConverted -> p == pConverted
 
-    prop "toPathPiece <=> fromPathPiece String" $ \(p::T.Text) ->
+    prop "toPathPiece <=> fromPathPiece Text" $ \(p::T.Text) ->
       case (fromPathPiece . toPathPiece) p of
         Nothing -> T.null p
         Just pConverted -> p == pConverted
 
-    prop "toPathPiece <=> fromPathPiece String" $ \(p::Int) ->
+    prop "toPathPiece <=> fromPathPiece Int" $ \(p::Int) ->
       case (fromPathPiece . toPathPiece) p of
         Nothing -> False
         Just pConverted -> p == pConverted
 
+    prop "toPathPiece <=> fromPathPiece Bool" $ \(p::Bool) ->
+      case (fromPathPiece . toPathPiece) p of
+        Nothing -> False
+        Just pConverted -> p == pConverted
+
+    prop "toPathPiece <=> fromPathPiece Maybe String" $ \(p::Maybe String) ->
+      case (fromPathPiece . toPathPiece) p of
+        Nothing -> False
+        Just pConverted -> p == pConverted
+
   describe "PathMultiPiece" $ do
     prop "toPathMultiPiece <=> fromPathMultiPiece String" $ \(p::[String]) ->
       p == (fromJust . fromPathMultiPiece . toPathMultiPiece) p
 
-    prop "toPathMultiPiece <=> fromPathMultiPiece String" $ \(p::[T.Text]) ->
+    prop "toPathMultiPiece <=> fromPathMultiPiece Text" $ \(p::[T.Text]) ->
       p == (fromJust . fromPathMultiPiece . toPathMultiPiece) p
 
 
@@ -51,12 +61,12 @@
         Nothing -> null p
         Just pConverted -> p == pConverted
 
-    prop "toPathPiece <=> fromPathPiece String" $ \(p::T.Text) ->
+    prop "toPathPiece <=> fromPathPiece Text" $ \(p::T.Text) ->
       case (fromPathPiece . toPathPiece) p of
         Nothing -> T.null p
         Just pConverted -> p == pConverted
 
-    prop "toPathPiece <=> fromPathPiece String" $ \(p::Int) ->
+    prop "toPathPiece <=> fromPathPiece Int" $ \(p::Int) ->
       case (fromPathPiece . toPathPiece) p of
         Nothing -> p < 0
         Just pConverted -> p == pConverted
@@ -65,5 +75,8 @@
     prop "toPathMultiPiece <=> fromPathMultiPiece String" $ \(p::[String]) ->
       p == (fromJust . fromPathMultiPiece . toPathMultiPiece) p
 
-    prop "toPathMultiPiece <=> fromPathMultiPiece String" $ \(p::[T.Text]) ->
+    prop "toPathMultiPiece <=> fromPathMultiPiece Text" $ \(p::[T.Text]) ->
       p == (fromJust . fromPathMultiPiece . toPathMultiPiece) p
+
+  it "bad ints are rejected" $ fromPathPiece (T.pack "123hello")
+    `shouldBe` (Nothing :: Maybe Int)