diff --git a/CODE_OF_CONDUCT.md b/CODE_OF_CONDUCT.md
new file mode 100644
index 0000000..0511f21
--- /dev/null
+++ b/CODE_OF_CONDUCT.md
@@ -0,0 +1,7 @@
+all repositories in these organizations:
+
+* [scala](https://github.com/scala)
+* [scalacenter](https://github.com/scalacenter)
+* [lampepfl](https://github.com/lampepfl)
+
+are covered by the Scala Code of Conduct: https://scala-lang.org/conduct/
diff --git a/build.sbt b/build.sbt
index bdd8506..c213b16 100644
--- a/build.sbt
+++ b/build.sbt
@@ -1,40 +1,29 @@
-// TODO Make it a cross project including Scala.js
 import ScalaModulePlugin._
 
 scalaModuleSettings
 
 name := "scala-collection-contrib"
-
 version := "0.1.0-SNAPSHOT"
 
 scalaVersionsByJvm in ThisBuild := {
-	val v213 = "2.13.0"
-	Map(
-		8 -> List(v213 -> true),
-		11 -> List(v213 -> false),
-		12 -> List(v213 -> false))
+  val v213 = "2.13.0"
+  Map(
+    8 -> List(v213 -> true),
+    11 -> List(v213 -> false),
+    12 -> List(v213 -> false))
 }
 
-scalacOptions ++= Seq("-opt-warnings", "-language:higherKinds")
-
+scalacOptions ++= Seq("-opt-warnings", "-language:higherKinds", "-deprecation", "-feature", "-Xfatal-warnings")
 scalacOptions in (Compile, doc) ++= Seq("-implicits", "-groups")
 
 testOptions += Tests.Argument(TestFrameworks.JUnit, "-q", "-v", "-s", "-a")
-
-parallelExecution in Test := false
+parallelExecution in Test := false  // why?
 
 homepage := Some(url("https://github.com/scala/scala-collection-contrib"))
-
 licenses := Seq("Apache-2.0" -> url("https://www.apache.org/licenses/LICENSE-2.0"))
 
-pomExtra :=
-    <developers>
-      <developer><id>julienrf</id><name>Julien Richard-Foy</name></developer>
-      <developer><id>szeiger</id><name>Stefan Zeiger</name></developer>
-    </developers>
-
 libraryDependencies ++= Seq(
-  "junit"            % "junit"           % "4.12",
+  "junit"            % "junit"           % "4.12"   % Test,
   "com.novocode"     % "junit-interface" % "0.11"   % Test,
-  "org.openjdk.jol"  % "jol-core"        % "0.9"
+  "org.openjdk.jol"  % "jol-core"        % "0.9"    % Test
 )
diff --git a/project/plugins.sbt b/project/plugins.sbt
index dda94d8..2fea6a4 100644
--- a/project/plugins.sbt
+++ b/project/plugins.sbt
@@ -1,6 +1,5 @@
-addSbtPlugin("org.xerial.sbt" % "sbt-sonatype" % "2.3")
+scalacOptions ++= Seq("-deprecation", "-feature", "-Xfatal-warnings")
 
+addSbtPlugin("org.xerial.sbt" % "sbt-sonatype" % "2.3")
 addSbtPlugin("com.jsuereth" % "sbt-pgp" % "1.1.2")
-
 addSbtPlugin("org.scala-lang.modules" % "sbt-scala-module" % "2.0.0")
-