diff --git a/yesod-auth/yesod-auth.cabal b/yesod-auth/yesod-auth.cabal
index 4c554448..aa0ab721 100644
--- a/yesod-auth/yesod-auth.cabal
+++ b/yesod-auth/yesod-auth.cabal
@@ -18,7 +18,7 @@ library
                    , authenticate            >= 1.3       && < 1.4
                    , bytestring              >= 0.9.1.4
                    , yesod-core              >= 1.1       && < 1.2
-                   , wai                     >= 1.3       && < 1.4
+                   , wai                     >= 1.3       && < 1.5
                    , template-haskell
                    , pureMD5                 >= 2.0       && < 2.2
                    , random                  >= 1.0.0.2  && < 1.1
diff --git a/yesod-core/Yesod/Internal/Core.hs b/yesod-core/Yesod/Internal/Core.hs
index c4a9796f..cd3f0c02 100644
--- a/yesod-core/Yesod/Internal/Core.hs
+++ b/yesod-core/Yesod/Internal/Core.hs
@@ -909,6 +909,9 @@ runFakeHandler fakeSessionMap logger master handler = liftIO $ do
           , W.queryString    = []
           , W.requestBody    = mempty
           , W.vault          = mempty
+#if MIN_VERSION_wai(1, 4, 0)
+          , W.requestBodyLength = W.KnownLength 0
+#endif
           }
       fakeRequest =
         Request
diff --git a/yesod-core/yesod-core.cabal b/yesod-core/yesod-core.cabal
index 7dbe69f6..1b6a5f73 100644
--- a/yesod-core/yesod-core.cabal
+++ b/yesod-core/yesod-core.cabal
@@ -50,7 +50,7 @@ library
     build-depends:   base                  >= 4.3      && < 5
                    , time                  >= 1.1.4
                    , yesod-routes          >= 1.1      && < 1.2
-                   , wai                   >= 1.3      && < 1.4
+                   , wai                   >= 1.3      && < 1.5
                    , wai-extra             >= 1.3      && < 1.4
                    , bytestring            >= 0.9.1.4
                    , text                  >= 0.7      && < 0.12
diff --git a/yesod-default/yesod-default.cabal b/yesod-default/yesod-default.cabal
index 2e1b4c3b..0513a8c5 100644
--- a/yesod-default/yesod-default.cabal
+++ b/yesod-default/yesod-default.cabal
@@ -20,7 +20,7 @@ library
     build-depends:   base                  >= 4       && < 5
                    , yesod-core            >= 1.1     && < 1.2
                    , warp                  >= 1.3     && < 1.4
-                   , wai                   >= 1.3     && < 1.4
+                   , wai                   >= 1.3     && < 1.5
                    , wai-extra             >= 1.3     && < 1.4
                    , bytestring            >= 0.9.1.4
                    , transformers          >= 0.2.2   && < 0.4
diff --git a/yesod-static/yesod-static.cabal b/yesod-static/yesod-static.cabal
index d055fe7a..70e0c016 100644
--- a/yesod-static/yesod-static.cabal
+++ b/yesod-static/yesod-static.cabal
@@ -31,7 +31,7 @@ library
                    , directory             >= 1.0
                    , transformers          >= 0.2.2
                    , wai-app-static        >= 1.3      && < 1.4
-                   , wai                   >= 1.3      && < 1.4
+                   , wai                   >= 1.3      && < 1.5
                    , text                  >= 0.9
                    , file-embed            >= 0.0.4.1  && < 0.5
                    , http-types            >= 0.7
diff --git a/yesod/yesod.cabal b/yesod/yesod.cabal
index d6594bdd..ea1a48bd 100644
--- a/yesod/yesod.cabal
+++ b/yesod/yesod.cabal
@@ -35,7 +35,7 @@ library
                    , yesod-default             >= 1.1.3    && < 1.2
                    , monad-control             >= 0.3      && < 0.4
                    , transformers              >= 0.2.2    && < 0.4
-                   , wai                       >= 1.3      && < 1.4
+                   , wai                       >= 1.3      && < 1.5
                    , wai-extra                 >= 1.3      && < 1.4
                    , hamlet                    >= 1.1      && < 1.2
                    , shakespeare-js            >= 1.0.2    && < 1.2