diff --git a/app/Main.hs b/app/Main.hs
index 12096b7..c6b6876 100644
--- a/app/Main.hs
+++ b/app/Main.hs
@@ -2,5 +2,29 @@ module Main (main) where
 
 import Server
 
+import Control.Applicative ((<|>))
+
+import qualified Data.Map as M
+
+import System.Environment (getArgs)
+
 main :: IO ()
-main = putStrLn "Try: http://localhost:8080/auth?scope=ID%20Profile&client_id=42&response_type=code&redirect_uri=localhost" >> runMockServer 8080
+main = do
+  args <- getArgs >>= flip buildArgs M.empty
+  port <- determinePort args
+  putStrLn $ "Try: http://localhost:" ++ show port ++ "/auth?scope=ID%20Profile&client_id=42&response_type=code&redirect_uri=localhost"
+  runMockServer port
+    where
+      buildArgs :: [String] -> M.Map String String -> IO (M.Map String String)
+      buildArgs [] m = return m
+      buildArgs (k:v:xs) m = return (M.insert k v m) >>= buildArgs xs
+      buildArgs _ _ = error "invalid command line args"
+
+      determinePort :: M.Map String String -> IO Int
+      determinePort args = do
+        case M.lookup "-p" args <|> M.lookup "--port" args of
+          Just port -> return $ read port
+          Nothing -> return 9443
+
+
+