diff --git a/project/ScalafixBuild.scala b/project/ScalafixBuild.scala
index d72d67897..3c1897ffd 100644
--- a/project/ScalafixBuild.scala
+++ b/project/ScalafixBuild.scala
@@ -279,6 +279,14 @@ object ScalafixBuild extends AutoPlugin with GhpagesKeys {
     Compile / console / scalacOptions :=
       compilerOptions.value :+ "-Yrepl-class-based",
     Compile / doc / scalacOptions ++= scaladocOptions,
+    Compile / unmanagedSourceDirectories ++= {
+      val dir = (Compile / sourceDirectory).value
+      scalaVersion.value match {
+        case `scala3LTS` => Seq(dir / "scala-3lts")
+        case `scala3Next` => Seq(dir / "scala-3next")
+        case _ => Nil
+      }
+    },
     // Don't package sources & docs when publishing locally as it adds a significant
     // overhead when testing because of publishLocalTransitive. Tweaking publishArtifact
     // would more readable, but it would also affect remote (sonatype) publishing.
diff --git a/scalafix-tests/input/src/main/scala-3lts/test/explicitResultTypes/BeforeScala3_4.scala b/scalafix-tests/input/src/main/scala-3lts/test/explicitResultTypes/BeforeScala3_4.scala
new file mode 100644
index 000000000..3a64696e4
--- /dev/null
+++ b/scalafix-tests/input/src/main/scala-3lts/test/explicitResultTypes/BeforeScala3_4.scala
@@ -0,0 +1,13 @@
+/*
+rules = ExplicitResultTypes
+ExplicitResultTypes.fetchScala3CompilerArtifactsOnVersionMismatch = true
+*/
+package test.explicitResultTypes
+
+object BeforeScala3_4 {
+  def foo = {
+    val xs = List(Some(1), None)
+    for Some(x) <- xs yield x
+  }
+}
+
diff --git a/scalafix-tests/input/src/main/scala-3next/test/explicitResultTypes/Scala3_5OrGreater.scala b/scalafix-tests/input/src/main/scala-3next/test/explicitResultTypes/Scala3_5OrGreater.scala
new file mode 100644
index 000000000..0ddaee0c0
--- /dev/null
+++ b/scalafix-tests/input/src/main/scala-3next/test/explicitResultTypes/Scala3_5OrGreater.scala
@@ -0,0 +1,10 @@
+/*
+rules = ExplicitResultTypes
+ExplicitResultTypes.skipSimpleDefinitions = false
+*/
+package test.explicitResultTypes
+
+object Scala3_5OrGreater {
+  def foo = 0b0010_0000
+}
+
diff --git a/scalafix-tests/output/src/main/scala-3lts/test/explicitResultTypes/BeforeScala3_4.scala b/scalafix-tests/output/src/main/scala-3lts/test/explicitResultTypes/BeforeScala3_4.scala
new file mode 100644
index 000000000..09b92d709
--- /dev/null
+++ b/scalafix-tests/output/src/main/scala-3lts/test/explicitResultTypes/BeforeScala3_4.scala
@@ -0,0 +1,8 @@
+package test.explicitResultTypes
+
+object BeforeScala3_4 {
+  def foo: List[Int] = {
+    val xs = List(Some(1), None)
+    for Some(x) <- xs yield x
+  }
+}
\ No newline at end of file
diff --git a/scalafix-tests/output/src/main/scala-3next/test/explicitResultTypes/Scala3_5OrGreater.scala b/scalafix-tests/output/src/main/scala-3next/test/explicitResultTypes/Scala3_5OrGreater.scala
new file mode 100644
index 000000000..c02646d1c
--- /dev/null
+++ b/scalafix-tests/output/src/main/scala-3next/test/explicitResultTypes/Scala3_5OrGreater.scala
@@ -0,0 +1,6 @@
+package test.explicitResultTypes
+
+object Scala3_5OrGreater {
+  def foo: Int = 0b0010_0000
+}
+