diff --git a/main/src/main/scala/sbt/Defaults.scala b/main/src/main/scala/sbt/Defaults.scala
index f55b51faa..0ad2bea7f 100644
--- a/main/src/main/scala/sbt/Defaults.scala
+++ b/main/src/main/scala/sbt/Defaults.scala
@@ -1778,7 +1778,10 @@ object Defaults extends BuildCommon {
         config,
         s.cacheStoreFactory,
         s.log,
-        sys.env.get("SOURCE_DATE_EPOCH").map(_.toLong * 1000).orElse(Some(0L))
+        sys.env
+          .get("SOURCE_DATE_EPOCH")
+          .map(_.toLong * 1000)
+          .orElse(Some(1262304000000L)) // 2010-01-01
       )
       config.jar
     }