--- a/jdk/src/share/classes/com/sun/tools/jdi/SDE.java	Wed Jun 19 13:00:53 2013 -0700
+++ b/jdk/src/share/classes/com/sun/tools/jdi/SDE.java	Wed Jun 19 14:02:38 2013 -0700
@@ -171,7 +171,7 @@
         }
 
         public boolean equals(Object obj) {
-            if ((obj != null) && (obj instanceof LineStratum)) {
+            if (obj instanceof LineStratum) {
                 LineStratum other = (LineStratum)obj;
                 return (lti == other.lti) &&
                        (sti == other.sti) &&
@@ -182,6 +182,11 @@
             }
         }
 
+        @Override
+        public int hashCode() {
+            return (lineNumber() * 17) ^ refType.hashCode();
+        }
+
         int lineNumber() {
             return stiLineNumber(sti, lti, jplsLine);
         }