diff --git a/.github/workflows/scala.yml b/.github/workflows/scala.yml
index e473d53..4caf95a 100644
--- a/.github/workflows/scala.yml
+++ b/.github/workflows/scala.yml
@@ -7,4 +7,4 @@ jobs:
       - uses: actions/checkout@v2
       - uses: olafurpg/setup-scala@v10
       - uses: coursier/cache-action@v3
-      - run: sbt clean headerCheck +test
+      - run: sbt clean sourceposJVM/headerCheck +test
diff --git a/build.sbt b/build.sbt
index 18811d2..01757f0 100644
--- a/build.sbt
+++ b/build.sbt
@@ -1,52 +1,68 @@
 
 // Our Scala versions.
-lazy val `scala-2.12`     = "2.12.12"
-lazy val `scala-2.13`     = "2.13.5"
-lazy val `scala-3.0`      = "3.0.0"
+lazy val `scala-2.12`     = "2.12.14"
+lazy val `scala-2.13`     = "2.13.6"
+lazy val `scala-3.0`      = "3.0.1"
 
 // Publishing
-name         := "sourcepos"
-organization := "org.tpolecat"
-licenses    ++= Seq(("MIT", url("http://opensource.org/licenses/MIT")))
-homepage     := Some(url("https://github.com/tpolecat/sourcepos"))
-developers   := List(
+ThisBuild / organization := "org.tpolecat"
+ThisBuild / licenses    ++= Seq(("MIT", url("http://opensource.org/licenses/MIT")))
+ThisBuild / homepage     := Some(url("https://github.com/tpolecat/sourcepos"))
+ThisBuild / developers   := List(
   Developer("tpolecat", "Rob Norris", "rob_norris@mac.com", url("http://www.tpolecat.org"))
 )
 
-// Headers
-headerMappings := headerMappings.value + (HeaderFileType.scala -> HeaderCommentStyle.cppStyleLineComment)
-headerLicense  := Some(HeaderLicense.Custom(
-  """|Copyright (c) 2020-2021 by Rob Norris
-     |This software is licensed under the MIT License (MIT).
-     |For more information see LICENSE or https://opensource.org/licenses/MIT
-     |""".stripMargin
+// Compilation
+ThisBuild / scalaVersion       := `scala-2.13`
+ThisBuild / crossScalaVersions := Seq(`scala-2.12`, `scala-2.13`, `scala-3.0`)
+
+lazy val root = project
+  .in(file("."))
+  .enablePlugins(NoPublishPlugin)
+  .settings(
+    Compile / unmanagedSourceDirectories := Seq.empty,
+    Test / unmanagedSourceDirectories := Seq.empty,
   )
-)
+  .aggregate(sourcepos.jvm, sourcepos.js)
 
-// Compilation
-scalaVersion       := `scala-2.13`
-crossScalaVersions := Seq(`scala-2.12`, `scala-2.13`, `scala-3.0`)
-Compile / doc     / scalacOptions --= Seq("-Xfatal-warnings")
-Compile / doc     / scalacOptions ++= Seq(
-  "-groups",
-  "-sourcepath", (LocalRootProject / baseDirectory).value.getAbsolutePath,
-  "-doc-source-url", "https://github.com/tpolecat/sourcepos/blob/v" + version.value + "€{FILE_PATH}.scala",
-)
+lazy val sourcepos = crossProject(JVMPlatform, JSPlatform)
+  .crossType(CrossType.Pure)
+  .in(file("."))
+  .enablePlugins(AutomateHeaderPlugin)
+  .settings(
+    name         := "sourcepos",
+
+    // Headers
+    headerMappings := headerMappings.value + (HeaderFileType.scala -> HeaderCommentStyle.cppStyleLineComment),
+    headerLicense  := Some(HeaderLicense.Custom(
+      """|Copyright (c) 2020-2021 by Rob Norris
+        |This software is licensed under the MIT License (MIT).
+        |For more information see LICENSE or https://opensource.org/licenses/MIT
+        |""".stripMargin
+      )
+    ),
 
-// MUnit
-libraryDependencies += "org.scalameta" %% "munit" % "0.7.26" % Test
-testFrameworks += new TestFramework("munit.Framework")
+    // Compilation
+    Compile / doc     / scalacOptions --= Seq("-Xfatal-warnings"),
+    Compile / doc     / scalacOptions ++= Seq(
+      "-groups",
+      "-sourcepath", (LocalRootProject / baseDirectory).value.getAbsolutePath,
+      "-doc-source-url", "https://github.com/tpolecat/sourcepos/blob/v" + version.value + "€{FILE_PATH}.scala",
+    ),
 
-// Scala 2 needs scala-reflect
-libraryDependencies ++= Seq("org.scala-lang" % "scala-reflect" % scalaVersion.value).filterNot(_ => scalaVersion.value.startsWith("3."))
+    // MUnit
+    libraryDependencies += "org.scalameta" %%% "munit" % "0.7.28" % Test,
+    testFrameworks += new TestFramework("munit.Framework"),
 
-// dottydoc really doesn't work at all right now
-Compile / doc / sources := {
-  val old = (Compile / doc / sources).value
-  if (scalaVersion.value.startsWith("3."))
-    Seq()
-  else
-    old
-}
+    // Scala 2 needs scala-reflect
+    libraryDependencies ++= Seq("org.scala-lang" % "scala-reflect" % scalaVersion.value).filterNot(_ => scalaVersion.value.startsWith("3.")),
 
-enablePlugins(AutomateHeaderPlugin)
+    // dottydoc really doesn't work at all right now
+    Compile / doc / sources := {
+      val old = (Compile / doc / sources).value
+      if (scalaVersion.value.startsWith("3."))
+        Seq()
+      else
+        old
+    }
+  )
diff --git a/project/build.properties b/project/build.properties
index 19479ba..10fd9ee 100644
--- a/project/build.properties
+++ b/project/build.properties
@@ -1 +1 @@
-sbt.version=1.5.2
+sbt.version=1.5.5
diff --git a/project/plugins.sbt b/project/plugins.sbt
index 7be8b3b..dee5626 100644
--- a/project/plugins.sbt
+++ b/project/plugins.sbt
@@ -1,3 +1,6 @@
 addSbtPlugin("com.geirsson"      % "sbt-ci-release" % "1.5.7")
 addSbtPlugin("de.heikoseeberger" % "sbt-header"     % "5.6.0")
 addSbtPlugin("com.timushev.sbt"  % "sbt-updates"    % "0.5.3")
+addSbtPlugin("org.portable-scala" % "sbt-scalajs-crossproject" % "1.1.0")
+addSbtPlugin("org.scala-js" % "sbt-scalajs" % "1.7.0")
+addSbtPlugin("io.chrisdavenport" % "sbt-no-publish" % "0.1.0")
diff --git a/src/test/scala/Example.scala b/src/test/scala/Example.scala
index 51325d1..1f9fb5f 100644
--- a/src/test/scala/Example.scala
+++ b/src/test/scala/Example.scala
@@ -1,4 +1,4 @@
-// Copyright (c) 2020 by Rob Norris
+// Copyright (c) 2020-2021 by Rob Norris
 // This software is licensed under the MIT License (MIT).
 // For more information see LICENSE or https://opensource.org/licenses/MIT
 
diff --git a/src/test/scala/Test.scala b/src/test/scala/Test.scala
index e08c588..7bc57c7 100644
--- a/src/test/scala/Test.scala
+++ b/src/test/scala/Test.scala
@@ -1,4 +1,4 @@
-// Copyright (c) 2020 by Rob Norris
+// Copyright (c) 2020-2021 by Rob Norris
 // This software is licensed under the MIT License (MIT).
 // For more information see LICENSE or https://opensource.org/licenses/MIT