diff --git a/ui/js/compareperf.js b/ui/js/compareperf.js
index 1580bc8ba36..026e1d73103 100644
--- a/ui/js/compareperf.js
+++ b/ui/js/compareperf.js
@@ -6,16 +6,30 @@
 
 perf.controller('CompareChooserCtrl', [
     '$state', '$stateParams', '$scope', 'ThRepositoryModel', 'ThResultSetModel',
+    'phCompareDefaultNewRepo', 'phCompareDefaultOriginalRepo',
     function CompareChooserCtrl($state, $stateParams, $scope,
-                                ThRepositoryModel, ThResultSetModel) {
+                                ThRepositoryModel, ThResultSetModel,
+                                phCompareDefaultNewRepo,
+                                phCompareDefaultOriginalRepo) {
         ThRepositoryModel.get_list().success(function(projects) {
             $scope.projects = projects;
             $scope.originalTipList = [];
             $scope.newTipList = [];
-            $scope.originalProject = _.findWhere(projects, { name: $stateParams.originalProject }) || projects[0];
-            $scope.newProject = _.findWhere(projects, { name: $stateParams.newProject }) || projects[0];
-            $scope.originalRevision = $stateParams.originalRevision ? $stateParams.originalRevision : '';
-            $scope.newRevision = $stateParams.newRevision ? $stateParams.newRevision : '';
+
+            $scope.originalProject = _.findWhere(projects, {
+                name: ($stateParams.originalProject ?
+                       $stateParams.originalProject : phCompareDefaultOriginalRepo)
+            }) || projects[0];
+            $scope.newProject = _.findWhere(projects, {
+                name: ($stateParams.newProject ?
+                       $stateParams.newProject : phCompareDefaultNewRepo)
+            }) || projects[0];
+
+            $scope.originalRevision = ($stateParams.originalRevision ?
+                                       $stateParams.originalRevision : '');
+            $scope.newRevision = ($stateParams.newRevision ?
+                                  $stateParams.newRevision : '');
+
             var getRevisionTips = function(projectName, list) {
                 // due to we push the revision data into list,
                 // so we need clear the data before we push new data into it.
diff --git a/ui/js/graphs.js b/ui/js/graphs.js
index 08eec7daf20..cd3263ebaec 100644
--- a/ui/js/graphs.js
+++ b/ui/js/graphs.js
@@ -729,15 +729,14 @@ perf.controller('GraphsCtrl', [
 perf.controller('TestChooserCtrl', function($scope, $modalInstance, $http,
                                             projects, optionCollectionMap,
                                             timeRange, thServiceDomain,
-                                            PhSeries, defaultProjectName,
-                                            defaultPlatform, testsDisplayed) {
+                                            thDefaultRepo, PhSeries,
+                                            defaultProjectName, defaultPlatform,
+                                            testsDisplayed) {
     $scope.timeRange = timeRange;
     $scope.projects = projects;
-    if (defaultProjectName) {
-        $scope.selectedProject = _.findWhere(projects, {name: defaultProjectName});
-    } else {
-        $scope.selectedProject = projects[0];
-    }
+    $scope.selectedProject = _.findWhere(projects, {
+        name: defaultProjectName ? defaultProjectName : thDefaultRepo
+    });
     $scope.loadingTestData = false;
 
     var series = [];
diff --git a/ui/js/values.js b/ui/js/values.js
index 1510d3e172d..3cf58e69ffd 100644
--- a/ui/js/values.js
+++ b/ui/js/values.js
@@ -139,6 +139,10 @@ treeherder.value("thDefaultRepo", "mozilla-inbound");
 
 treeherder.value("thDateFormat", "EEE MMM d, H:mm:ss");
 
+treeherder.value("phCompareDefaultOriginalRepo", "mozilla-inbound");
+
+treeherder.value("phCompareDefaultNewRepo", "try");
+
 treeherder.value("phTimeRanges", [
       { "value":86400, "text": "Last day" },
       { "value":604800, "text": "Last 7 days" },