diff --git a/compiler/test/dotty/tools/utils.scala b/compiler/test/dotty/tools/utils.scala
index a9792bf2f43c..f6d568ecce85 100644
--- a/compiler/test/dotty/tools/utils.scala
+++ b/compiler/test/dotty/tools/utils.scala
@@ -2,6 +2,7 @@ package dotty
 package tools
 
 import java.io.File
+import java.nio.charset.Charset
 import java.nio.charset.StandardCharsets.UTF_8
 import java.nio.file.{Files, Path => JPath}
 
@@ -45,8 +46,8 @@ def assertThrows[T <: Throwable: ClassTag](p: T => Boolean)(body: => Any): Unit
     case NonFatal(other) => throw AssertionError(s"Wrong exception: expected ${implicitly[ClassTag[T]]} but was ${other.getClass.getName}").tap(_.addSuppressed(other))
 end assertThrows
 
-def toolArgsFor(files: List[JPath]): List[String] =
-  files.flatMap(path => toolArgsParse(Files.lines(path, UTF_8).limit(10).toScala(List)))
+def toolArgsFor(files: List[JPath], charset: Charset = UTF_8): List[String] =
+  files.flatMap(path => toolArgsParse(Files.lines(path, charset).limit(10).toScala(List)))
 
 // Inspect the first 10 of the given lines for compiler options of the form
 // `// scalac: args`, `/* scalac: args`, ` * scalac: args`.
@@ -58,7 +59,8 @@ def toolArgsParse(lines: List[String]): List[String] = {
   val endc = "*" + "/"    // be forgiving of /* scalac: ... */
   def stripped(s: String) = s.substring(s.indexOf(tag) + tag.length).stripSuffix(endc)
   val args = lines.to(LazyList).take(10).filter { s =>
-       s.contains("// " + tag)
+       s.contains("//" + tag)
+    || s.contains("// " + tag)
     || s.contains("/* " + tag)
     || s.contains(" * " + tag)
     // but avoid picking up comments like "% scalac ./a.scala" and "$ scalac a.scala"
diff --git a/compiler/test/dotty/tools/vulpix/ParallelTesting.scala b/compiler/test/dotty/tools/vulpix/ParallelTesting.scala
index 4ba1229feecb..0efcb4c64fc5 100644
--- a/compiler/test/dotty/tools/vulpix/ParallelTesting.scala
+++ b/compiler/test/dotty/tools/vulpix/ParallelTesting.scala
@@ -6,7 +6,7 @@ import java.io.{File => JFile, IOException}
 import java.lang.System.{lineSeparator => EOL}
 import java.nio.file.StandardCopyOption.REPLACE_EXISTING
 import java.nio.file.{Files, NoSuchFileException, Path, Paths}
-import java.nio.charset.StandardCharsets
+import java.nio.charset.{Charset, StandardCharsets}
 import java.text.SimpleDateFormat
 import java.util.{HashMap, Timer, TimerTask}
 import java.util.concurrent.{TimeUnit, TimeoutException, Executors => JExecutors}
@@ -441,15 +441,17 @@ trait ParallelTesting extends RunnerOrchestration { self =>
           throw e
 
     protected def compile(files0: Array[JFile], flags0: TestFlags, suppressErrors: Boolean, targetDir: JFile): TestReporter = {
-      val flags = flags0.and("-d", targetDir.getPath)
-        .withClasspath(targetDir.getPath)
-
       def flattenFiles(f: JFile): Array[JFile] =
         if (f.isDirectory) f.listFiles.flatMap(flattenFiles)
         else Array(f)
 
       val files: Array[JFile] = files0.flatMap(flattenFiles)
 
+      val flags = flags0
+        .and(toolArgsFor(files.toList.map(_.toPath), getCharsetFromEncodingOpt(flags0)): _*)
+        .and("-d", targetDir.getPath)
+        .withClasspath(targetDir.getPath)
+
       def compileWithJavac(fs: Array[String]) = if (fs.nonEmpty) {
         val fullArgs = Array(
           "javac",
@@ -1358,6 +1360,11 @@ trait ParallelTesting extends RunnerOrchestration { self =>
     // Create a CompilationTest and let the user decide whether to execute a pos or a neg test
     new CompilationTest(targets)
   }
+
+  private def getCharsetFromEncodingOpt(flags: TestFlags) =
+    flags.options.sliding(2).collectFirst {
+      case Array("-encoding", encoding) => Charset.forName(encoding)
+    }.getOrElse(StandardCharsets.UTF_8)
 }
 
 object ParallelTesting {
diff --git a/tests/neg/literals.scala b/tests/neg/literals.scala
index 4b847a74df66..8e062c19351b 100644
--- a/tests/neg/literals.scala
+++ b/tests/neg/literals.scala
@@ -2,7 +2,7 @@ trait RejectedLiterals {
   def missingHex: Int    = { 0x }        // error: invalid literal number
 }
 /*
-// scalac: -Ywarn-octal-literal -Xfatal-warnings -deprecation
+// nsc: -Ywarn-octal-literal -Xfatal-warnings -deprecation
 trait RejectedLiterals {
 
   def missingHex: Int    = { 0x }        // line 4: was: not reported, taken as zero
diff --git a/tests/run/1938-2.scala b/tests/run/1938-2.scala
index 32e4c4518b96..143a94705455 100644
--- a/tests/run/1938-2.scala
+++ b/tests/run/1938-2.scala
@@ -1,6 +1,6 @@
 object ProdNonEmpty {
   def _1: Int = 0
-  def _2: String = "???" // Slight variation with scalac: this test passes
+  def _2: String = "???" // Slight variation with nsc: this test passes
                          // with ??? here. I think dotty behavior is fine
                          // according to the spec given that methods involved
                          // in pattern matching should be pure.