diff --git a/jbake/src/de/tobiasroeser/mill/jbake/JBakeWorkerSubProcessImpl.scala b/jbake/src/de/tobiasroeser/mill/jbake/JBakeWorkerSubProcessImpl.scala
index e8ebbe1..9145e72 100644
--- a/jbake/src/de/tobiasroeser/mill/jbake/JBakeWorkerSubProcessImpl.scala
+++ b/jbake/src/de/tobiasroeser/mill/jbake/JBakeWorkerSubProcessImpl.scala
@@ -14,7 +14,7 @@ class JBakeWorkerSubProcessImpl(classpath: Seq[Path])(implicit ctx: Log) extends
   def runJbakeMain(cwd: Path, args: Shellable*): Unit = {
     val proc = os.proc(
       "java",
-      "-cp", classpath.mkString(":"),
+      "-cp", classpath.mkString(java.io.File.pathSeparator),
       "org.jbake.launcher.Main",
       args
     )