diff --git a/config/build.sbt b/config/build.sbt
index 99bf6cbc..9c453abf 100644
--- a/config/build.sbt
+++ b/config/build.sbt
@@ -33,3 +33,5 @@ seq(javadocSettings: _*)
 JavadocKeys.javadocOptions += "-exclude com.typesafe.config.impl"
 
 doc in Compile <<= JavadocKeys.javadoc
+
+javacOptions in Compile ++= Seq("-source", "1.6", "-target", "1.6")