diff --git a/dist/tests/equation.js b/dist/tests/equation.js
index a086517..8600135 100644
--- a/dist/tests/equation.js
+++ b/dist/tests/equation.js
@@ -14,6 +14,7 @@ describe('Equations', function () {
 
     _expect.expect(equation(2)).to.equal(4);
 
+    // Issue #10
     var subtraction = _M2['default'].equation('x - 3');
     _expect.expect(subtraction(10)).to.equal(7);
   });
diff --git a/package.json b/package.json
index 127004f..9993bdb 100644
--- a/package.json
+++ b/package.json
@@ -26,6 +26,7 @@
     "grunt-contrib-watch": "^0.6.1",
     "grunt-eslint": "^11.0.0",
     "grunt-mocha-test": "^0.12.7",
-    "mocha": "^2.2.4"
+    "mocha": "^2.2.4",
+    "babel": "^5.8.21"
   }
 }