diff --git a/compiler/src/dotty/tools/dotc/fromtasty/Debug.scala b/compiler/src/dotty/tools/dotc/fromtasty/Debug.scala
index c249f00a2368..f2d9adca1e50 100644
--- a/compiler/src/dotty/tools/dotc/fromtasty/Debug.scala
+++ b/compiler/src/dotty/tools/dotc/fromtasty/Debug.scala
@@ -6,6 +6,7 @@ import scala.util.control.NonFatal
 
 import dotty.tools.io.Directory
 
+import java.io.{File => JFile}
 import java.nio.file.{Files, Paths}
 
 object Debug {
@@ -65,7 +66,7 @@ object Debug {
 
   private def insertClasspathInArgs(args: List[String], cp: String): List[String] = {
     val (beforeCp, fromCp) = args.span(_ != "-classpath")
-    val classpath = fromCp.drop(1).headOption.fold(cp)(_ + ":" + cp)
+    val classpath = fromCp.drop(1).headOption.fold(cp)(_ + JFile.pathSeparator + cp)
     "-classpath" :: classpath :: beforeCp ::: fromCp.drop(2)
   }
 }
diff --git a/compiler/src/dotty/tools/dotc/quoted/QuoteCompiler.scala b/compiler/src/dotty/tools/dotc/quoted/QuoteCompiler.scala
index 8fca5cdbb0d7..21b442ac4dfc 100644
--- a/compiler/src/dotty/tools/dotc/quoted/QuoteCompiler.scala
+++ b/compiler/src/dotty/tools/dotc/quoted/QuoteCompiler.scala
@@ -17,7 +17,7 @@ import dotty.tools.dotc.transform.Staging
 import dotty.tools.dotc.typer.FrontEnd
 import dotty.tools.dotc.util.Positions.Position
 import dotty.tools.dotc.util.SourceFile
-import dotty.tools.io.{Path, PlainFile}
+import dotty.tools.io.{Path, VirtualFile}
 
 import scala.quoted.{Expr, Type}
 
@@ -67,7 +67,7 @@ class QuoteCompiler extends Compiler {
       */
     private def inClass(expr: Expr[_])(implicit ctx: Context): Tree = {
       val pos = Position(0)
-      val assocFile = new PlainFile(Path("<quote>"))
+      val assocFile = new VirtualFile("<quote>")
 
       val cls = ctx.newCompleteClassSymbol(defn.RootClass, outputClassName, EmptyFlags,
         defn.ObjectType :: Nil, newScope, coord = pos, assocFile = assocFile).entered.asClass