diff --git a/project/Version.scala b/project/Version.scala
index 07f76ed01c..13706a876d 100644
--- a/project/Version.scala
+++ b/project/Version.scala
@@ -12,10 +12,10 @@ import sbt.Keys._
 object Version {
 
   def versionSettings: Seq[Setting[_]] = inConfig(Compile)(Seq(
-    resourceGenerators <+= generateVersion(resourceManaged, _ / "version.conf",
+    resourceGenerators += generateVersion(resourceManaged, _ / "version.conf",
       """|akka.version = "%s"
          |"""),
-    sourceGenerators <+= generateVersion(sourceManaged, _ / "akka" / "Version.scala",
+    sourceGenerators += generateVersion(sourceManaged, _ / "akka" / "Version.scala",
       """|package akka
          |
          |object Version {