diff --git a/PaymentServer.cabal b/PaymentServer.cabal
index bd1e969adacfcf51184c4b46849c6709f1e34a58..246e201fce4d53e2d84cbdc50a75dfad18d0549d 100644
--- a/PaymentServer.cabal
+++ b/PaymentServer.cabal
@@ -26,8 +26,10 @@ library
                      , optparse-applicative
                      , aeson
                      , bytestring
+                     , utf8-string
                      , servant
                      , servant-server
+                     , http-types
                      , wai
                      , wai-extra
                      , wai-cors
diff --git a/src/PaymentServer/Main.hs b/src/PaymentServer/Main.hs
index 0c0dd73b58c858d65d7f6dff04d2963b3afafa61..274bc945f2464845b78147bfea284262ece349dd 100644
--- a/src/PaymentServer/Main.hs
+++ b/src/PaymentServer/Main.hs
@@ -6,6 +6,9 @@ module PaymentServer.Main
   ( main
   ) where
 
+import Control.Exception.Base
+  ( SomeException
+  )
 import Text.Printf
   ( printf
   )
@@ -18,10 +21,15 @@ import Data.Text
 import Data.Default
   ( def
   )
+import Network.HTTP.Types.Status
+  ( status500
+  )
 import Network.Wai.Handler.Warp
   ( Port
   , defaultSettings
   , setPort
+  , setOnException
+  , setOnExceptionResponse
   , run
   )
 import Network.Wai.Handler.WarpTLS
@@ -30,6 +38,9 @@ import Network.Wai.Handler.WarpTLS
   )
 import Network.Wai
   ( Application
+  , Request
+  , Response
+  , responseLBS
   )
 import Network.Wai.Middleware.Cors
   ( Origin
@@ -79,6 +90,7 @@ import System.Exit
 import Data.Semigroup ((<>))
 import qualified Data.Text.IO as TIO
 import qualified Data.ByteString as B
+import qualified Data.ByteString.Lazy.UTF8 as LBS
 
 data Issuer =
   Trivial
@@ -197,7 +209,18 @@ getRunner endpoint =
     (TLSEndpoint portNumber certificatePath chainPath keyPath) ->
       let
         tlsSettings = tlsSettingsChain certificatePath (maybeToList chainPath) keyPath
-        settings = setPort portNumber defaultSettings
+        onException :: Maybe Request -> SomeException -> IO ()
+        onException _ exc = do
+          print "onException"
+          print exc
+          return ()
+        onExceptionResponse :: SomeException -> Response
+        onExceptionResponse = (responseLBS status500 []) . LBS.fromString . ("exception: " ++) . show
+        settings =
+          setPort portNumber .
+          setOnException onException .
+          setOnExceptionResponse onExceptionResponse $
+          defaultSettings
       in
         runTLS tlsSettings settings
 
diff --git a/src/PaymentServer/Processors/Stripe.hs b/src/PaymentServer/Processors/Stripe.hs
index 57137eda62fd1e9437607a15f47546f93b1cb603..9ee9c2730c334161a434f46179802a7e11efad5a 100644
--- a/src/PaymentServer/Processors/Stripe.hs
+++ b/src/PaymentServer/Processors/Stripe.hs
@@ -37,7 +37,7 @@ import Servant
   , Handler
   , err400
   , err500
-  , ServerError(errBody)
+  , ServerError(errHTTPCode, errBody)
   , throwError
   )
 import Servant.API
@@ -171,7 +171,14 @@ charge d key (Charges token voucher amount currency) = do
             else
             throwError err500 { errBody = "Voucher code mismatch" }
         _ -> throwError err400 { errBody = "Voucher code not found" }
-    Left StripeError {} -> throwError err400 { errBody = "Stripe charge didn't succeed" }
+    Left StripeError {} ->
+      let
+        errCode = (read "foo") :: Int
+      in
+        throwError err400
+        { errHTTPCode = errCode
+        , errBody = "Stripe charge didn't succeed"
+        }
     where
       getCurrency :: Text -> Handler Currency
       getCurrency maybeCurrency =