diff --git a/services/sync/modules/engines/bookmarks.js b/services/sync/modules/engines/bookmarks.js
index 7504bc3d2048..5841090b8fee 100644
--- a/services/sync/modules/engines/bookmarks.js
+++ b/services/sync/modules/engines/bookmarks.js
@@ -267,8 +267,18 @@ BookmarksEngine.prototype = {
         let id = this._store.idForGUID(guid);
         switch (Svc.Bookmark.getItemType(id)) {
           case Svc.Bookmark.TYPE_BOOKMARK:
-            key = "b" + Svc.Bookmark.getBookmarkURI(id).spec + ":" +
-              Svc.Bookmark.getItemTitle(id);
+
+            // Smart bookmarks map to their annotation value.
+            let queryId;
+            try {
+              queryId = Utils.anno(id, SMART_BOOKMARKS_ANNO);
+            } catch(ex) {}
+            
+            if (queryId)
+              key = "q" + queryId;
+            else
+              key = "b" + Svc.Bookmark.getBookmarkURI(id).spec + ":" +
+                    Svc.Bookmark.getItemTitle(id);
             break;
           case Svc.Bookmark.TYPE_FOLDER:
             key = "f" + Svc.Bookmark.getItemTitle(id);
@@ -302,9 +312,19 @@ BookmarksEngine.prototype = {
       return this._lazyMap = function(item) {
         // Figure out if we have something to key with
         let key;
+        let altKey;
         switch (item.type) {
-          case "bookmark":
           case "query":
+            // Prior to Bug 610501, records didn't carry their Smart Bookmark
+            // anno, so we won't be able to dupe them correctly. This altKey
+            // hack should get them to dupe correctly.
+            if (item.queryId) {
+              key = "q" + item.queryId;
+              altKey = "b" + item.bmkUri + ":" + item.title;
+              break;
+            }
+            // No queryID? Fall through to the regular bookmark case.
+          case "bookmark":
           case "microsummary":
             key = "b" + item.bmkUri + ":" + item.title;
             break;
@@ -322,9 +342,29 @@ BookmarksEngine.prototype = {
         // Give the guid if we have the matching pair
         this._log.trace("Finding mapping: " + item.parentName + ", " + key);
         let parent = lazyMap[item.parentName];
-        let dupe = parent && parent[key];
-        this._log.trace("Mapped dupe: " + dupe);
-        return dupe;
+        
+        if (!parent) {
+          this._log.trace("No parent => no dupe.");
+          return undefined;
+        }
+          
+        let dupe = parent[key];
+        
+        if (dupe) {
+          this._log.trace("Mapped dupe: " + dupe);
+          return dupe;
+        }
+        
+        if (altKey) {
+          dupe = parent[altKey];
+          if (dupe) {
+            this._log.trace("Mapped dupe using altKey " + altKey + ": " + dupe);
+            return dupe;
+          }
+        }
+        
+        this._log.trace("No dupe found for key " + key + "/" + altKey + ".");
+        return undefined;
       };
     });
 
diff --git a/services/sync/tests/unit/test_bookmark_smart_bookmarks.js b/services/sync/tests/unit/test_bookmark_smart_bookmarks.js
index 370b15fbde40..25f0b6bbd52e 100644
--- a/services/sync/tests/unit/test_bookmark_smart_bookmarks.js
+++ b/services/sync/tests/unit/test_bookmark_smart_bookmarks.js
@@ -178,6 +178,68 @@ function test_annotation_uploaded() {
   }
 }
 
+function test_smart_bookmarks_duped() {
+  let parent = PlacesUtils.toolbarFolderId;
+  let uri =
+    Utils.makeURI("place:redirectsMode=" +
+                  Ci.nsINavHistoryQueryOptions.REDIRECTS_MODE_TARGET +
+                  "&sort=" +
+                  Ci.nsINavHistoryQueryOptions.SORT_BY_VISITCOUNT_DESCENDING +
+                  "&maxResults=10");
+  let title = "Most Visited";
+  let mostVisitedID = newSmartBookmark(parent, uri, -1, title, "MostVisited");
+  let mostVisitedGUID = store.GUIDForId(mostVisitedID);
+  
+  let record = store.createRecord(mostVisitedGUID);
+  
+  _("Prepare sync.");
+  Svc.Prefs.set("username", "foo");
+  Service.serverURL = "http://localhost:8080/";
+  Service.clusterURL = "http://localhost:8080/";
+
+  let collection = new ServerCollection({}, true);
+  let global = new ServerWBO('global',
+                             {engines: {bookmarks: {version: engine.version,
+                                                    syncID: engine.syncID}}});
+  let server = httpd_setup({
+    "/1.0/foo/storage/meta/global": global.handler(),
+    "/1.0/foo/storage/bookmarks": collection.handler()
+  });
+  
+  try {
+    engine._syncStartup();
+    
+    _("Verify that lazyMap uses the anno, discovering a dupe regardless of URI.");
+    do_check_eq(mostVisitedGUID, engine._lazyMap(record));
+    
+    record.bmkUri = "http://foo/";
+    do_check_eq(mostVisitedGUID, engine._lazyMap(record));
+    do_check_neq(Svc.Bookmark.getBookmarkURI(mostVisitedID).spec, record.bmkUri);
+    
+    _("Verify that different annos don't dupe.");
+    let other = new BookmarkQuery("bookmarks", "abcdefabcdef");
+    other.queryId = "LeastVisited";
+    other.parentName = "Bookmarks Toolbar";
+    other.bmkUri = "place:foo";
+    other.title = "";
+    do_check_eq(undefined, engine._findDupe(other));
+    
+    _("Handle records without a queryId entry.");
+    record.bmkUri = uri;
+    delete record.queryId;
+    do_check_eq(mostVisitedGUID, engine._lazyMap(record));
+    
+    engine._syncFinish();
+
+  } finally {
+    // Clean up.
+    store.wipe();
+    server.stop(do_test_finished);
+    Svc.Prefs.resetBranch("");
+    Records.clearCache();
+  }
+}
+
 function run_test() {
   initTestLogging("Trace");
   Log4Moz.repository.getLogger("Engine.Bookmarks").level = Log4Moz.Level.Trace;
@@ -185,4 +247,5 @@ function run_test() {
   CollectionKeys.generateNewKeys();
 
   test_annotation_uploaded();
+  test_smart_bookmarks_duped();
 }