--- a/jdk/src/share/classes/java/time/temporal/IsoFields.java	Fri Apr 18 17:37:13 2014 -0400
+++ b/jdk/src/share/classes/java/time/temporal/IsoFields.java	Sat Apr 12 14:54:44 2014 +0100
@@ -535,11 +535,17 @@
                 if (isSupportedBy(temporal) == false) {
                     throw new UnsupportedTemporalTypeException("Unsupported field: WeekBasedYear");
                 }
-                int newVal = range().checkValidIntValue(newValue, WEEK_BASED_YEAR);  // strict check
+                int newWby = range().checkValidIntValue(newValue, WEEK_BASED_YEAR);  // strict check
                 LocalDate date = LocalDate.from(temporal);
+                int dow = date.get(DAY_OF_WEEK);
                 int week = getWeek(date);
-                date = date.withDayOfYear(180).withYear(newVal).with(WEEK_OF_WEEK_BASED_YEAR, week);
-                return (R) date.with(date);
+                if (week == 53 && getWeekRange(newWby) == 52) {
+                    week = 52;
+                }
+                LocalDate resolved = LocalDate.of(newWby, 1, 4);  // 4th is guaranteed to be in week one
+                int days = (dow - resolved.get(DAY_OF_WEEK)) + ((week - 1) * 7);
+                resolved = resolved.plusDays(days);
+                return (R) temporal.with(resolved);
             }
             @Override
             public String toString() {
@@ -577,12 +583,16 @@
 
         private static ValueRange getWeekRange(LocalDate date) {
             int wby = getWeekBasedYear(date);
-            date = date.withDayOfYear(1).withYear(wby);
+            return ValueRange.of(1, getWeekRange(wby));
+        }
+
+        private static int getWeekRange(int wby) {
+            LocalDate date = LocalDate.of(wby, 1, 1);
             // 53 weeks if standard year starts on Thursday, or Wed in a leap year
             if (date.getDayOfWeek() == THURSDAY || (date.getDayOfWeek() == WEDNESDAY && date.isLeapYear())) {
-                return ValueRange.of(1, 53);
+                return 53;
             }
-            return ValueRange.of(1, 52);
+            return 52;
         }
 
         private static int getWeek(LocalDate date) {