diff --git a/src/git.js b/src/git.js
index e7a11f1a..c66193dc 100644
--- a/src/git.js
+++ b/src/git.js
@@ -7,13 +7,13 @@ var uniqueId = (function() {
   };
 })();
 
-function GitEngine() {
+function GitEngine(options) {
   this.rootCommit = null;
   this.refs = {};
   this.HEAD = null;
   this.id_gen = 0;
   this.branches = [];
-  this.collection = commitCollection;
+  this.collection = options.collection;
 
   // global variable to keep track of the options given
   // along with the command call.
@@ -28,7 +28,7 @@ function GitEngine() {
 GitEngine.prototype.init = function() {
   // make an initial commit and a master branch
   this.rootCommit = new Commit({rootCommit: true});
-  commitCollection.add(this.rootCommit);
+  this.collection.add(this.rootCommit);
 
   this.refs[this.rootCommit.get('id')] = this.rootCommit;
 
diff --git a/src/mine.js b/src/mine.js
index 99585289..df35f48b 100644
--- a/src/mine.js
+++ b/src/mine.js
@@ -34,8 +34,12 @@ $(document).ready(function(){
     collection: commandCollection
   });
 
-  gitEngine = new GitEngine();
-  gitVisuals = new GitVisuals();
+  gitEngine = new GitEngine({
+    collection: commitCollection
+  });
+  gitVisuals = new GitVisuals({
+    collection: commitCollection
+  });
 
   $('#commandTextField').focus();
 });
diff --git a/src/visuals.js b/src/visuals.js
index 5ea8c122..726822f6 100644
--- a/src/visuals.js
+++ b/src/visuals.js
@@ -1,5 +1,5 @@
-function GitVisuals() {
-  this.collection = commitCollection;
+function GitVisuals(options) {
+  this.collection = options.collection;
 
   this.collection.on('change', _.bind(this.collectionChanged, this));
   events.on('drawGitVisuals', _.bind(this.drawVisuals, this));