diff --git a/icfp2015.cabal b/icfp2015.cabal
index f4718b4..c3b1002 100644
--- a/icfp2015.cabal
+++ b/icfp2015.cabal
@@ -68,3 +68,5 @@ executable icfp2015
   -- Base language which the package is written in.
   default-language:    Haskell2010
 
+  ghc-options: -O3 -threaded
+