diff --git a/oauth-1.0a.js b/oauth-1.0a.js
index 5c15dd4..3ef053f 100644
--- a/oauth-1.0a.js
+++ b/oauth-1.0a.js
@@ -2,6 +2,10 @@ if (typeof(module) !== 'undefined' && typeof(exports) !== 'undefined') {
     module.exports = OAuth;
 }
 
+if (typeof(URL) === 'undefined') {
+    var URL = require('whatwg-url').URL;
+}
+
 /**
  * Constructor
  * @param {Object} opts consumer key and secret
@@ -194,7 +198,11 @@ OAuth.prototype.getSigningKey = function(token_secret) {
  * @return {String}
  */
 OAuth.prototype.getBaseUrl = function(url) {
-    return url.split('?')[0];
+    var parsed = new URL(url);
+
+    parsed.search = '';
+
+    return parsed.toString();
 };
 
 /**
diff --git a/package.json b/package.json
index ba878f3..dc9f1d3 100644
--- a/package.json
+++ b/package.json
@@ -24,5 +24,8 @@
     "istanbul": "^0.4.5",
     "mocha": "^4.0.1",
     "request": "~2.33.0"
+  },
+  "dependencies": {
+    "whatwg-url": "^6.4.0"
   }
 }
diff --git a/test/getBaseUrl.js b/test/getBaseUrl.js
new file mode 100644
index 0000000..b788d51
--- /dev/null
+++ b/test/getBaseUrl.js
@@ -0,0 +1,33 @@
+var expect = require('chai').expect;
+var OAuth = require('../oauth-1.0a');
+
+describe('#getBaseUrl', function() {
+	var oauth = new OAuth({
+		consumer: {}
+	});
+
+	beforeEach(function () {
+		oauth = new OAuth({
+			consumer: {}
+		});
+  });
+
+  it('should return base url', function () {
+    expect(oauth.getBaseUrl('http://example.com/path/')).to.equal('http://example.com/path/');
+    expect(oauth.getBaseUrl('http://example.com/path/?foo=bar')).to.equal('http://example.com/path/');
+  });
+
+  it('should exclude default port number', function () {
+    expect(oauth.getBaseUrl('http://example.com/')).to.equal('http://example.com/');
+    expect(oauth.getBaseUrl('http://example.com:80/')).to.equal('http://example.com/');
+    expect(oauth.getBaseUrl('https://example.com/')).to.equal('https://example.com/');
+    expect(oauth.getBaseUrl('https://example.com:443/')).to.equal('https://example.com/');
+  });
+
+  it('should include non-default port number', function () {
+    expect(oauth.getBaseUrl('http://example.com:8080/')).to.equal('http://example.com:8080/');
+    expect(oauth.getBaseUrl('http://example.com:443/')).to.equal('http://example.com:443/');
+    expect(oauth.getBaseUrl('https://example.com:8080/')).to.equal('https://example.com:8080/');
+    expect(oauth.getBaseUrl('https://example.com:80/')).to.equal('https://example.com:80/');
+  });
+});