diff --git a/project/Build.scala b/project/Build.scala
index caeaf3b7f47d..9c99e5d81e04 100644
--- a/project/Build.scala
+++ b/project/Build.scala
@@ -496,6 +496,8 @@ object Build {
         }
       }.evaluated,
 
+      Compile / mainClass := Some("dotty.tools.dotc.Main"),
+
       scala := {
         val args: List[String] = spaceDelimited("<arg>").parsed.toList
         val externalDeps = externalCompilerClasspathTask.value