diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 1f90b49..b65dbc3 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -9,7 +9,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        scala-version: [2.13.x]
+        scala-version: [2.13.x, 3.3.x]
         java-version: [8, 11, 17, 21]
     steps:
       - uses: actions/checkout@v4
@@ -18,6 +18,6 @@ jobs:
           distribution: temurin
           java-version: ${{ matrix.java-version }}
       - name: Run tests
-        run: sbt ++${{ matrix.scala-version }} clean versionPolicyCheck coverage test coverageReport
+        run: sbt ++${{ matrix.scala-version }} clean coverage test coverageReport
       - name: Upload coverage report
         run: bash <(curl -s https://codecov.io/bash)
diff --git a/.scalafmt.conf b/.scalafmt.conf
index 7a60977..b79a3b6 100644
--- a/.scalafmt.conf
+++ b/.scalafmt.conf
@@ -10,4 +10,4 @@ rewriteTokens = {
   "→": "->"
   "←": "<-"
 }
-runner.dialect = scala213
+runner.dialect = scala213source3
diff --git a/build.sbt b/build.sbt
index 2a5dbdf..09f29f7 100644
--- a/build.sbt
+++ b/build.sbt
@@ -13,8 +13,10 @@ developers := List(
   )
 )
 
-crossScalaVersions := List("2.13.15")
-scalaVersion       := crossScalaVersions.value.last
+scalaVersion := "2.13.15"
+crossScalaVersions += "3.3.4"
+
+scalacOptions += "-Xsource:3"
 
 ThisBuild / versionScheme          := Some("semver-spec")
 ThisBuild / versionPolicyIntention := Compatibility.BinaryCompatible
diff --git a/src/main/scala/nl/gn0s1s/isbn/Isbn.scala b/src/main/scala/nl/gn0s1s/isbn/Isbn.scala
index 747d6a8..0079b61 100644
--- a/src/main/scala/nl/gn0s1s/isbn/Isbn.scala
+++ b/src/main/scala/nl/gn0s1s/isbn/Isbn.scala
@@ -1,5 +1,8 @@
 package nl.gn0s1s.isbn
 
+import scala.annotation.nowarn
+
+@nowarn
 final case class Isbn private (value: String) {
   lazy val Array(prefixElement, registrationGroupElement, registrantElement, publicationElement, checkDigit) =
     toHyphenatedIsbn13.split('-')
diff --git a/src/test/scala/nl/gn0s1s/isbn/HyphenationSuite.scala b/src/test/scala/nl/gn0s1s/isbn/HyphenationSuite.scala
index 0ccf7ed..368a413 100644
--- a/src/test/scala/nl/gn0s1s/isbn/HyphenationSuite.scala
+++ b/src/test/scala/nl/gn0s1s/isbn/HyphenationSuite.scala
@@ -1,7 +1,7 @@
 package nl.gn0s1s.isbn
 
 import munit.ScalaCheckSuite
-import org.scalacheck.Prop._
+import org.scalacheck.Prop.*
 
 class HyphenationSuite extends ScalaCheckSuite {
   property("can convert to a hyphenated isbn-13") {
diff --git a/src/test/scala/nl/gn0s1s/isbn/IsbnSuite.scala b/src/test/scala/nl/gn0s1s/isbn/IsbnSuite.scala
index 25aaf57..f82c233 100644
--- a/src/test/scala/nl/gn0s1s/isbn/IsbnSuite.scala
+++ b/src/test/scala/nl/gn0s1s/isbn/IsbnSuite.scala
@@ -1,7 +1,7 @@
 package nl.gn0s1s.isbn
 
 import munit.ScalaCheckSuite
-import org.scalacheck.Prop._
+import org.scalacheck.Prop.*
 
 class IsbnSuite extends ScalaCheckSuite {
   property("accepts isbn-13s") {