diff --git a/hanafuda.cabal b/hanafuda.cabal
index 85d71c6..f7e2094 100644
--- a/hanafuda.cabal
+++ b/hanafuda.cabal
@@ -41,5 +41,6 @@ library
                      , containers
                      , mtl
                      , random
+  ghc-options:         -Wall
   hs-source-dirs:      src
   default-language:    Haskell2010