diff --git a/karma.conf.js b/karma.conf.js
index ad435f07a..96cd0cf38 100644
--- a/karma.conf.js
+++ b/karma.conf.js
@@ -11,7 +11,8 @@ module.exports = {
   // list of files / patterns to load in the browser
   files: [
     "test/browser/*.js",
-    "test/both/*.js"
+    "test/both/*.js",
+    {pattern: "test/spec/v2/*.json", watched: false, included: false, served: true, nocache: false}
   ],
 
 
diff --git a/lib/client.js b/lib/client.js
index 437ee893e..1e1cf5bea 100644
--- a/lib/client.js
+++ b/lib/client.js
@@ -462,7 +462,7 @@ SwaggerClient.prototype.parseUri = function (uri) {
   var parts = urlParseRE.exec(uri);
 
   return {
-    scheme: parts[4].replace(':',''),
+    scheme: parts[4] ? parts[4].replace(':','') : undefined,
     host: parts[11],
     port: parts[12],
     path: parts[15]
diff --git a/test/browser/http.js b/test/browser/http.js
index f62105630..d04785191 100644
--- a/test/browser/http.js
+++ b/test/browser/http.js
@@ -171,4 +171,17 @@ describe('yaml http', function () {
               });
         });
   });
+
+  it('should support relative spec URLs as per #645', function(done) {
+    try {
+      new Swagger({
+        url: '/base/test/spec/v2/test.json',
+        usePromise: true
+      }).then(function(client) {
+        done();
+      });
+    } catch (exception) {
+      done(exception);
+    }
+  });
 });