diff --git a/functions/diff.js b/functions/diff.js
index d15b1def..f5ca9779 100644
--- a/functions/diff.js
+++ b/functions/diff.js
@@ -1,8 +1,8 @@
-const parse = require('./parse')
+const SemVer = require('../classes/semver')
 
 const diff = (version1, version2) => {
-  const v1 = parse(version1)
-  const v2 = parse(version2)
+  const v1 = new SemVer(version1)
+  const v2 = new SemVer(version2)
   const comparison = v1.compare(v2)
 
   if (comparison === 0) {
diff --git a/test/functions/diff.js b/test/functions/diff.js
index aa35c3d0..74a80569 100644
--- a/test/functions/diff.js
+++ b/test/functions/diff.js
@@ -43,3 +43,13 @@ test('diff versions test', (t) => {
 
   t.end()
 })
+
+test('throws on bad version', (t) => {
+  t.throws(() => {
+    diff('bad', '1.2.3')
+  }, {
+    message: 'Invalid Version: bad',
+    name: 'TypeError',
+  })
+  t.end()
+})