diff --git a/src/Routing/Duplex.purs b/src/Routing/Duplex.purs
index d412681..d426f1d 100644
--- a/src/Routing/Duplex.purs
+++ b/src/Routing/Duplex.purs
@@ -8,6 +8,7 @@ module Routing.Duplex
   , path
   , root
   , end
+  , end'
   , segment
   , param
   , flag
@@ -141,6 +142,11 @@ root = path ""
 end :: forall a b. RouteDuplex a b -> RouteDuplex a b
 end (RouteDuplex enc dec) = RouteDuplex enc (dec <* Parser.end)
 
+-- | Strict version of `end codec` will only suceed if `codec` succeeds and there are no
+-- | additional path segments, hashes, parameters remaining to be processed.
+end' :: forall a b. RouteDuplex a b -> RouteDuplex a b
+end' (RouteDuplex enc dec) = RouteDuplex enc (dec <* Parser.end')
+
 -- | Consumes or prints a single path segment.
 -- | **Note:** [URI encoding and decoding](https://en.wikipedia.org/wiki/Percent-encoding) is done automatically.
 -- |
diff --git a/src/Routing/Duplex/Generic.purs b/src/Routing/Duplex/Generic.purs
index 5243f19..5811f28 100644
--- a/src/Routing/Duplex/Generic.purs
+++ b/src/Routing/Duplex/Generic.purs
@@ -8,7 +8,7 @@ import Data.Profunctor (dimap)
 import Data.Symbol (class IsSymbol)
 import Prim.Row as Row
 import Record as Record
-import Routing.Duplex (RouteDuplex(..), RouteDuplex', end)
+import Routing.Duplex (RouteDuplex(..), RouteDuplex', end, end')
 import Type.Proxy (Proxy(..))
 
 -- | Builds a parser/printer from a record, where each record field corresponds
@@ -25,6 +25,19 @@ sum
   -> RouteDuplex' a
 sum = dimap from to <<< gRouteDuplex end
 
+-- | Builds a parser/printer from a record, where each record field corresponds
+-- | to a constructor name for your data type.
+-- |
+-- | Note: this implicitly inserts calls to `end'` for each constructor, making
+-- | the parser only valid for parsing URI suffixes. To parse URI prefixes, use `sumPrefix`.
+sum'
+  :: forall a rep r
+   . Generic a rep
+  => GRouteDuplex rep r
+  => { | r }
+  -> RouteDuplex' a
+sum' = dimap from to <<< gRouteDuplex end'
+
 -- | A variation of `sum` that does not implicitly add an `end` to each branch.
 -- | This is useful for defining sub-parsers that may consume only some of the
 -- | URI segments, leaving the rest for subsequent parsers.
diff --git a/src/Routing/Duplex/Parser.purs b/src/Routing/Duplex/Parser.purs
index 9c96745..d013293 100644
--- a/src/Routing/Duplex/Parser.purs
+++ b/src/Routing/Duplex/Parser.purs
@@ -19,6 +19,7 @@ module Routing.Duplex.Parser
   , boolean
   , hash
   , end
+  , end'
   , module Routing.Duplex.Types
   ) where
 
@@ -42,6 +43,7 @@ import Data.String (Pattern(..), split)
 import Data.String.CodeUnits as String
 import Data.Traversable (traverse)
 import Data.Tuple (Tuple(..))
+import Data.Tuple.Nested ((/\))
 import JSURI (decodeURIComponent)
 import Routing.Duplex.Types (RouteParams, RouteState)
 
@@ -59,8 +61,11 @@ instance showRouteResult :: Show a => Show (RouteResult a) where
 data RouteError
   = Expected String String
   | ExpectedEndOfPath String
+  | ExpectedNoHash String
+  | ExpectedNoParams RouteParams
   | MissingParam String
   | MalformedURIComponent String
+  | MissingHash
   | EndOfPath
 
 derive instance eqRouteError :: Eq RouteError
@@ -185,7 +190,12 @@ parsePath =
   splitNonEmpty p s = split p s
 
   toRouteState (Tuple (Tuple segments params) h) =
-    { segments, params, hash: h }
+    { segments
+    , params
+    , hash: case h of
+        "" -> Nothing
+        h' -> Just h'
+    }
 
   splitAt k p str =
     case String.indexOf (Pattern p) str of
@@ -213,7 +223,7 @@ take = Chomp \state ->
 param :: String -> RouteParser String
 param key = Chomp \state ->
   case lookup key state.params of
-    Just a -> Success state a
+    Just a -> Success (state { params = Array.delete (key /\ a) state.params }) a
     _ -> Fail $ MissingParam key
 
 flag :: String -> RouteParser Boolean
@@ -259,7 +269,9 @@ int :: String -> Either String Int
 int = maybe (Left "Int") Right <<< Int.fromString
 
 hash :: RouteParser String
-hash = Chomp \state -> Success state state.hash
+hash = Chomp \state -> case state.hash of
+  Nothing -> Fail MissingHash
+  Just h -> Success (state { hash = Nothing }) h
 
 end :: RouteParser Unit
 end = Chomp \state ->
@@ -267,6 +279,14 @@ end = Chomp \state ->
     Nothing -> Success state unit
     Just str -> Fail (ExpectedEndOfPath str)
 
+end' :: RouteParser Unit
+end' = Chomp \state ->
+  case (Array.head state.segments /\ state.hash /\ state.params) of
+    (Nothing /\ Nothing /\ []) -> Success state unit
+    (Just str /\ _ /\ _) -> Fail (ExpectedEndOfPath str)
+    (_ /\ Just h /\ _) -> Fail (ExpectedNoHash h)
+    (_ /\ _ /\ params) -> Fail (ExpectedNoParams params)
+
 boolean :: String -> Either String Boolean
 boolean = case _ of
   "true" -> Right true
diff --git a/src/Routing/Duplex/Printer.purs b/src/Routing/Duplex/Printer.purs
index cac2b96..30efa06 100644
--- a/src/Routing/Duplex/Printer.purs
+++ b/src/Routing/Duplex/Printer.purs
@@ -41,7 +41,9 @@ flag key val
   | otherwise = mempty
 
 hash :: String -> RoutePrinter
-hash h = RoutePrinter _ { hash = h }
+hash h
+  | h == "" = RoutePrinter _ { hash = Nothing }
+  | otherwise = RoutePrinter _ { hash = Just h }
 
 run :: RoutePrinter -> String
 run = printPath <<< applyFlipped emptyRouteState <<< unwrap
@@ -60,5 +62,5 @@ printPath { segments, params, hash: hash' } =
   printParam key "" = encodeURIComponent key
   printParam key val = encodeURIComponent key <> Just "=" <> encodeURIComponent val
 
-  printHash "" = ""
-  printHash h = "#" <> h
+  printHash Nothing = ""
+  printHash (Just h) = "#" <> h
diff --git a/src/Routing/Duplex/Types.purs b/src/Routing/Duplex/Types.purs
index b70d092..1afbd5a 100644
--- a/src/Routing/Duplex/Types.purs
+++ b/src/Routing/Duplex/Types.purs
@@ -1,5 +1,6 @@
 module Routing.Duplex.Types where
 
+import Data.Maybe (Maybe(..))
 import Data.Tuple (Tuple)
 
 type RouteParams = Array (Tuple String String)
@@ -7,12 +8,12 @@ type RouteParams = Array (Tuple String String)
 type RouteState =
   { segments :: Array String
   , params :: RouteParams
-  , hash :: String
+  , hash :: Maybe String
   }
 
 emptyRouteState :: RouteState
 emptyRouteState =
   { segments: []
   , params: []
-  , hash: ""
+  , hash: Nothing
   }
diff --git a/test/Unit.purs b/test/Unit.purs
index 23b4af8..4ea1953 100644
--- a/test/Unit.purs
+++ b/test/Unit.purs
@@ -51,6 +51,7 @@ combinatorUnitTests = do
 
   -- hash
   assertEqual { actual: parse hash "abc#def", expected: Right "def" }
+  assertEqual { actual: parse hash "abc", expected: Left MissingHash }
 
   -- suffix
   assertEqual { actual: parse (suffix segment "latest") "release/latest", expected: Right "release" }