diff --git a/internal/util-collection/src/main/scala/sbt/internal/util/Settings.scala b/internal/util-collection/src/main/scala/sbt/internal/util/Settings.scala
index 5aa6f18e6..a46abc0b9 100644
--- a/internal/util-collection/src/main/scala/sbt/internal/util/Settings.scala
+++ b/internal/util-collection/src/main/scala/sbt/internal/util/Settings.scala
@@ -234,7 +234,7 @@ trait Init[ScopeType] {
     if (s.definitive) s :: Nil else ss :+ s
 
   def addLocal(init: Seq[Setting[_]])(implicit scopeLocal: ScopeLocal): Seq[Setting[_]] =
-    init.flatMap(_.dependencies flatMap scopeLocal) ++ init
+    init.par.map(_.dependencies flatMap scopeLocal).toVector.flatten ++ init
 
   def delegate(sMap: ScopedMap)(
       implicit delegates: ScopeType => Seq[ScopeType],