diff --git a/Devel.hs b/Devel.hs
--- a/Devel.hs
+++ b/Devel.hs
@@ -161,7 +161,11 @@
 #endif
                         $ ProxyDest "127.0.0.1" appPort)
                 def
+#if MIN_VERSION_wai(3, 0, 0)
+                    { wpsOnExc = \e req f -> onExc e req >>= f
+#else
                     { wpsOnExc = onExc
+#endif
                     , wpsTimeout =
                         if proxyTimeout opts == 0
                             then Nothing
diff --git a/yesod-bin.cabal b/yesod-bin.cabal
--- a/yesod-bin.cabal
+++ b/yesod-bin.cabal
@@ -1,5 +1,5 @@
 name:            yesod-bin
-version:         1.2.9.4
+version:         1.2.10
 license:         MIT
 license-file:    LICENSE
 author:          Michael Snoyman <michael@snoyman.com>