diff --git a/build.sbt b/build.sbt
index 5d7d3da..a1dc8e0 100644
--- a/build.sbt
+++ b/build.sbt
@@ -22,10 +22,16 @@ scalaXmlVersion            := "1.0.4"
 
 scalaCheckVersion          := "1.11.6"
 
-// TODO: enable "-Xfatal-warnings" for nightlies,
-// off by default because we don't want to break scala/scala pr validation due to deprecation
-// don't use for doc scope, scaladoc warnings are not to be reckoned with
-scalacOptions in (Compile, compile) ++= Seq("-optimize", "-feature", "-deprecation", "-unchecked", "-Xlint")
+// TODO: eliminate "-deprecation:false" for nightlies,
+//   included by default because we don't want to break scala/scala pr validation
+scalacOptions ++=
+  Seq("-feature", "-deprecation:false", "-unchecked", "-Xlint", "-Xfatal-warnings") ++
+  (CrossVersion.partialVersion(scalaVersion.value) match {
+    case Some((2, scalaMajor)) if scalaMajor < 12 =>
+      Seq("-optimize")
+    case _ =>
+      Seq()  // maybe "-Yopt:l:classpath" eventually?
+  })
 
 // dependencies
 // versions involved in integration builds / that change frequently should be keys, set above!
diff --git a/src/main/scala/scala/tools/partest/nest/Runner.scala b/src/main/scala/scala/tools/partest/nest/Runner.scala
index dc13d76..2251c15 100644
--- a/src/main/scala/scala/tools/partest/nest/Runner.scala
+++ b/src/main/scala/scala/tools/partest/nest/Runner.scala
@@ -312,7 +312,7 @@ class Runner(val testFile: File, val suiteRunner: SuiteRunner) {
    *
    *  File paths are detected using the absolute path of the test root.
    *  A string that looks like a file path is normalized by replacing
-   *  the leading segments (the root) with "$ROOT" and by replacing
+   *  the leading segments (the root) with "\$ROOT" and by replacing
    *  any Windows backslashes with the one true file separator char.
    */
   def normalizeLog() {
@@ -765,7 +765,7 @@ class SuiteRunner(
 
   def banner = {
     val baseDir = fileManager.compilerUnderTest.parent.toString
-    def relativize(path: String) = path.replace(baseDir, "$baseDir").replace(PathSettings.srcDir.toString, "$sourceDir")
+    def relativize(path: String) = path.replace(baseDir, s"$$baseDir").replace(PathSettings.srcDir.toString, "$sourceDir")
     val vmBin  = javaHome + fileSeparator + "bin"
     val vmName = "%s (build %s, %s)".format(javaVmName, javaVmVersion, javaVmInfo)