diff --git a/build.sbt b/build.sbt
index 95705fe74..057add441 100644
--- a/build.sbt
+++ b/build.sbt
@@ -11,9 +11,9 @@ scalaVersion               := crossScalaVersions.value.head
 crossScalaVersions         := {
   val java = System.getProperty("java.version")
   if (java.startsWith("1.6.") || java.startsWith("1.7."))
-    Seq("2.11.7", "2.12.0-M1")
+    Seq("2.11.7", "2.12.0-M4")
   else if (java.startsWith("1.8.") || java.startsWith("1.9."))
-    Seq("2.12.0-M2")
+    Seq("2.12.0-M4")
   else
     sys.error(s"don't know what Scala versions to build on $java")
 }
@@ -36,4 +36,4 @@ libraryDependencies += "com.novocode" % "junit-interface" % "0.10" % "test"
 // used in CompilerErrors test
 libraryDependencies += ("org.scala-lang" % "scala-compiler" % scalaVersion.value % "test").exclude("org.scala-lang.modules", s"scala-xml*")
 
-mimaPreviousVersion := Some("1.0.1")
+mimaPreviousVersion := Some("1.0.6")