diff --git a/.travis.yml b/.travis.yml
index 9fce93b77..57da53855 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -22,6 +22,7 @@ addons:
 jdk:
   - openjdk6
   - oraclejdk8
+  - oraclejdk9
 
 notifications:
   email: adriaan.moors@lightbend.com
diff --git a/admin/build.sh b/admin/build.sh
index 037672bd4..7c24d3020 100755
--- a/admin/build.sh
+++ b/admin/build.sh
@@ -50,4 +50,4 @@ if [[ "$TRAVIS_TAG" =~ $tagPat ]]; then
   openssl aes-256-cbc -K $K -iv $IV -in admin/secring.asc.enc -out admin/secring.asc -d
 fi
 
-sbt "$publishVersion" "$publishScalaVersion" clean update +test +publishLocal $extraTarget
+sbt -Dsbt.scala.version=2.10.7 "$publishVersion" "$publishScalaVersion" clean update +test +publishLocal $extraTarget
diff --git a/build.sbt b/build.sbt
index 572b09969..f2c989398 100644
--- a/build.sbt
+++ b/build.sbt
@@ -1,7 +1,7 @@
 import ScalaModulePlugin._
 
 scalaVersionsByJvm in ThisBuild := {
-  val v211 = "2.11.11"
+  val v211 = "2.11.12"
   val v212 = "2.12.3"
   val v213 = "2.13.0-M2"
   Map(
@@ -25,13 +25,23 @@ lazy val xml = crossProject.in(file("."))
     scalacOptions         ++= "-deprecation:false -feature -Xlint:-stars-align,-nullary-unit,_".split("\\s+").to[Seq],
     scalacOptions in Test  += "-Xxml:coalescing",
 
-    apiMappings ++= Map(
-      scalaInstance.value.libraryJar
-        -> url(s"http://www.scala-lang.org/api/${scalaVersion.value}/"),
-      // http://stackoverflow.com/questions/16934488
-      file(System.getProperty("sun.boot.class.path").split(java.io.File.pathSeparator).filter(_.endsWith(java.io.File.separator + "rt.jar")).head)
-        -> url("http://docs.oracle.com/javase/8/docs/api")
-    )
+    apiMappings ++= {
+      Map(
+        scalaInstance.value.libraryJar
+          -> url(s"http://www.scala-lang.org/api/${scalaVersion.value}/")
+      ) ++ {
+        // http://stackoverflow.com/questions/16934488
+        Option(System.getProperty("sun.boot.class.path"))
+          .map(path =>
+            Map(
+              file(path
+                .split(java.io.File.pathSeparator)
+                .filter(_.endsWith(java.io.File.separator + "rt.jar")).head)
+              -> url("http://docs.oracle.com/javase/8/docs/api")
+            ))
+          .getOrElse(Map.empty)
+      }
+    }
   )
   .jvmSettings(
     OsgiKeys.exportPackage := Seq(s"scala.xml.*;version=${version.value}"),