diff --git a/ChangeLog.md b/ChangeLog.md
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,3 +1,8 @@
+## 3.2.18
+
+* Make `testWithApplicationSettings` actually use the settings passed.
+  [#677](https://github.com/yesodweb/wai/pull/677).
+
 ## 3.2.16
 
 * In `testWithApplication`, don't `throwTo` ignorable exceptions
diff --git a/Network/Wai/Handler/Warp/WithApplication.hs b/Network/Wai/Handler/Warp/WithApplication.hs
--- a/Network/Wai/Handler/Warp/WithApplication.hs
+++ b/Network/Wai/Handler/Warp/WithApplication.hs
@@ -68,7 +68,7 @@
 --
 -- @since 3.2.7
 testWithApplicationSettings :: Settings -> IO Application -> (Port -> IO a) -> IO a
-testWithApplicationSettings _settings mkApp action = do
+testWithApplicationSettings settings mkApp action = do
   callingThread <- myThreadId
   app <- mkApp
   let wrappedApp request respond =
@@ -77,7 +77,7 @@
             (defaultShouldDisplayException e)
             (throwTo callingThread e)
           throwIO e
-  withApplication (return wrappedApp) action
+  withApplicationSettings settings (return wrappedApp) action
 
 data Waiter a
   = Waiter {
diff --git a/warp.cabal b/warp.cabal
--- a/warp.cabal
+++ b/warp.cabal
@@ -1,5 +1,5 @@
 Name:                warp
-Version:             3.2.17
+Version:             3.2.18
 Synopsis:            A fast, light-weight web server for WAI applications.
 License:             MIT
 License-file:        LICENSE