diff -r 5d77df3d30d1 -r a4118f530263 src/Pure/System/classpath.scala
--- a/src/Pure/System/classpath.scala	Sun Feb 18 12:32:54 2024 +0100
+++ b/src/Pure/System/classpath.scala	Sun Feb 18 12:33:43 2024 +0100
@@ -55,7 +55,8 @@
     val this_class_loader = this.getClass.getClassLoader
     if (dynamic_jars.isEmpty) this_class_loader
     else {
-      new URLClassLoader(dynamic_jars.map(File.url).toArray, this_class_loader) {
+      val dynamic_jars_url = dynamic_jars.map(file => File.url(file).java_url)
+      new URLClassLoader(dynamic_jars_url.toArray, this_class_loader) {
         override def finalize(): Unit = {
           for (jar <- dynamic_jars) {
             try { jar.delete() }