diff --git a/compile/src/main/scala/sbt/compiler/CompilerArguments.scala b/compile/src/main/scala/sbt/compiler/CompilerArguments.scala
index e3916fcb9..6a2a41056 100644
--- a/compile/src/main/scala/sbt/compiler/CompilerArguments.scala
+++ b/compile/src/main/scala/sbt/compiler/CompilerArguments.scala
@@ -45,13 +45,14 @@ final class CompilerArguments(scalaInstance: xsbti.compile.ScalaInstance, cp: xs
   /** Add the correct Scala library jar to the boot classpath if `addLibrary` is true.*/
   def createBootClasspath(addLibrary: Boolean) =
     {
-      def findBoot: String = {
-        import scala.collection.JavaConverters._
-        System.getProperties.asScala.iterator.collectFirst {
-          case (k, v) if k.endsWith(".boot.class.path") => v
-        }.getOrElse("")
-      }
-      val originalBoot = System.getProperty("sun.boot.class.path", findBoot)
+      def findBoot: String =
+        {
+          import scala.collection.JavaConverters._
+          System.getProperties.asScala.iterator.collectFirst {
+            case (k, v) if k.endsWith(".boot.class.path") => v
+          }.getOrElse("")
+        }
+      val originalBoot = Option(System.getProperty("sun.boot.class.path")).getOrElse(findBoot)
       if (addLibrary) {
         val newBootPrefix = if (originalBoot.isEmpty) "" else originalBoot + File.pathSeparator
         newBootPrefix + scalaInstance.libraryJar.getAbsolutePath