--- old/test/langtools/tools/javac/switchextra/CaseTest.java	2018-12-05 13:52:37.538718228 -0800
+++ new/test/langtools/tools/javac/switchextra/CaseTest.java	2018-12-05 13:52:37.350812221 -0800
@@ -136,7 +136,7 @@
 
         StringWriter out = new StringWriter();
         JavacTask ct = (JavacTask) tool.getTask(out, null, noErrors,
-            List.of("-XDdev", "--enable-preview", "-source", "12"), null,
+            List.of("-XDdev", "--enable-preview", "-source", "13"), null,
             Arrays.asList(new MyFileObject(code)));
         return ct.parse().iterator().next();
     }