diff --git a/src/Network/Wai/Routing/Predicate/Capture.hs b/src/Network/Wai/Routing/Predicate/Capture.hs
--- a/src/Network/Wai/Routing/Predicate/Capture.hs
+++ b/src/Network/Wai/Routing/Predicate/Capture.hs
@@ -57,6 +57,6 @@
     type FVal HasCapture   = Error
     type TVal HasCapture   = ()
     apply (HasCapture x) r =
-        if null (lookupQuery x r)
+        if null (lookupCapture x r)
             then F (err status400 ("Missing path parameter '" <> x <> "'."))
             else T 0 ()
diff --git a/wai-routing.cabal b/wai-routing.cabal
--- a/wai-routing.cabal
+++ b/wai-routing.cabal
@@ -1,5 +1,5 @@
 name:                wai-routing
-version:             0.3
+version:             0.3.1
 synopsis:            Declarative routing for WAI.
 license:             OtherLicense
 license-file:        LICENSE