--- a/test/jdk/java/util/concurrent/Exchanger/LoopHelpers.java	Tue Jan 16 18:24:32 2018 -0800
+++ b/test/jdk/java/util/concurrent/Exchanger/LoopHelpers.java	Tue Jan 16 18:28:39 2018 -0800
@@ -95,7 +95,7 @@
         String num = Long.toString(n);
         if (num.length() >= field.length())
             return num;
-        StringBuffer b = new StringBuffer(field);
+        StringBuilder b = new StringBuilder(field);
         b.replace(b.length()-num.length(), b.length(), num);
         return b.toString();
     }