diff --git a/.travis.yml b/.travis.yml
index 749e9653..8a9e4f77 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -9,6 +9,7 @@ scala:
   - 2.12.12
   - 2.13.3
   - 3.0.0-M2
+  - 3.0.0-M3
 
 env:
   - SCALAJS_VERSION=       ADOPTOPENJDK=8
diff --git a/build.sbt b/build.sbt
index 0b541040..a3e220bc 100644
--- a/build.sbt
+++ b/build.sbt
@@ -31,8 +31,10 @@ lazy val root = project
     compat212JS,
     compat213JVM,
     compat213JS,
-    compat30JVM,
-    compat30JS,
+    compat30M2JVM,
+    compat30M2JS,
+    compat30M3JVM,
+    compat30M3JS,
     `scalafix-data211`,
     `scalafix-data212`,
     `scalafix-data213`,
@@ -53,7 +55,8 @@ lazy val junit = libraryDependencies += "com.novocode" % "junit-interface" % "0.
 lazy val scala211 = "2.11.12"
 lazy val scala212 = "2.12.12"
 lazy val scala213 = "2.13.3"
-lazy val scala30  = "3.0.0-M2"
+lazy val scala30M2  = "3.0.0-M2"
+lazy val scala30M3  = "3.0.0-M3"
 
 lazy val compat = MultiScalaCrossProject(JSPlatform, JVMPlatform, NativePlatform)(
   "compat",
@@ -106,7 +109,8 @@ lazy val compat = MultiScalaCrossProject(JSPlatform, JVMPlatform, NativePlatform
 val compat211 = compat(scala211)
 val compat212 = compat(scala212)
 val compat213 = compat(scala213)
-val compat30  = compat(scala30)
+val compat30M2  = compat(scala30M2)
+val compat30M3  = compat(scala30M3)
 
 lazy val compat211JVM    = compat211.jvm
 lazy val compat211JS     = compat211.js
@@ -115,8 +119,10 @@ lazy val compat212JVM    = compat212.jvm
 lazy val compat212JS     = compat212.js
 lazy val compat213JVM    = compat213.jvm
 lazy val compat213JS     = compat213.js
-lazy val compat30JVM     = compat30.jvm
-lazy val compat30JS      = compat30.js
+lazy val compat30M2JVM   = compat30M2.jvm
+lazy val compat30M2JS    = compat30M2.js
+lazy val compat30M3JVM   = compat30M3.jvm
+lazy val compat30M3JS    = compat30M3.js
 
 lazy val `binary-compat-old` = project
   .in(file("binary-compat/old"))
diff --git a/project/MultiScalaProject.scala b/project/MultiScalaProject.scala
index ff52206c..95634714 100644
--- a/project/MultiScalaProject.scala
+++ b/project/MultiScalaProject.scala
@@ -28,8 +28,13 @@ import java.io.File
  */
 trait MultiScala {
   def majorMinor(in: String): String = {
-    val Array(major, minor, _) = in.split("\\.")
-    major + minor
+    val milestoneRegex = raw"\d*-(M\d*)".r
+    val Array(major, minor, milestone) = in.split("\\.")
+    val mExt = milestone match {
+      case milestoneRegex(m) => m
+      case _ => ""
+    }
+    major + minor + mExt
   }
 
   def projectIdPerScala(name: String, scalaV: String): String = s"$name${majorMinor(scalaV)}"
diff --git a/project/plugins.sbt b/project/plugins.sbt
index 9f930ad1..be4cef1b 100644
--- a/project/plugins.sbt
+++ b/project/plugins.sbt
@@ -4,7 +4,7 @@ val scalaJSVersion =
 val scalaNativeVersion =
   Option(System.getenv("SCALANATIVE_VERSION")).filter(_.nonEmpty).getOrElse("0.3.9")
 
-addSbtPlugin("ch.epfl.lamp"           % "sbt-dotty"                     % "0.5.0")
+addSbtPlugin("ch.epfl.lamp"           % "sbt-dotty"                     % "0.5.1")
 addSbtPlugin("org.scala-js"           % "sbt-scalajs"                   % scalaJSVersion)
 addSbtPlugin("org.portable-scala"     % "sbt-scalajs-crossproject"      % crossVer)
 addSbtPlugin("org.scala-native"       % "sbt-scala-native"              % scalaNativeVersion)