diff --git a/Makefile b/Makefile
index 5f82a16..a38edbb 100644
--- a/Makefile
+++ b/Makefile
@@ -7,6 +7,7 @@
 .PHONY : init
 init :
 	cabal sandbox init
+	cabal install happy
 	cabal install --only-dependencies --enable-tests
 	cabal configure --enable-tests