diff --git a/build.sbt b/build.sbt
index a4111c9..128c675 100644
--- a/build.sbt
+++ b/build.sbt
@@ -6,4 +6,4 @@ scalaVersion := "2.9.1"
 
 libraryDependencies += "org.scalatest" % "scalatest_2.9.1" % "1.6.1" % "test"
 
-libraryDependencies += "org.scalaz" %% "scalaz-core" % "6.0.4"
\ No newline at end of file
+libraryDependencies += "org.scalaz" % "scalaz-core_2.9.1" % "6.0.4"
\ No newline at end of file