diff --git a/Cakefile b/Cakefile
index d23d8ff..f0d15a6 100644
--- a/Cakefile
+++ b/Cakefile
@@ -20,7 +20,7 @@ task 'test', ->
       ssl_cert ->
         test_cases = glob.sync 'test/js/**/*_test.js'
         test_cases.sort()  # Consistent test case order.
-        run 'node_modules/.bin/mocha --colors --slow 200 --timeout 1000 ' +
+        run 'node_modules/.bin/mocha --colors --slow 200 --timeout 1000 --exit ' +
             "--require test/js/helpers/setup.js #{test_cases.join(' ')}"
 
 task 'webtest', ->
diff --git a/package.json b/package.json
index b723776..558fad9 100644
--- a/package.json
+++ b/package.json
@@ -26,7 +26,9 @@
   "engines": {
     "node": ">= 6"
   },
-  "dependencies": {},
+  "dependencies": {
+    "native-url": "^0.3.4"
+  },
   "devDependencies": {
     "async": ">=3.0.1",
     "chai": ">=4.2.0",
diff --git a/src/001-xml_http_request.coffee b/src/001-xml_http_request.coffee
index 3e448b4..82d5a01 100644
--- a/src/001-xml_http_request.coffee
+++ b/src/001-xml_http_request.coffee
@@ -6,7 +6,7 @@
 http = require 'http'
 https = require 'https'
 os = require 'os'
-url = require 'url'
+url = require 'native-url'
 
 # The ECMAScript HTTP API.
 #
@@ -105,6 +105,8 @@ class XMLHttpRequest extends XMLHttpRequestEventTarget
       throw new SecurityError "HTTP method #{method} is not allowed in XHR"
 
     xhrUrl = @_parseUrl url
+    xhrUrl.path = encodeURI xhrUrl.path
+
     async = true if async is undefined
 
     switch @readyState
diff --git a/test/src/helpers/xhr_server.coffee b/test/src/helpers/xhr_server.coffee
index 5dcb0ea..db35810 100644
--- a/test/src/helpers/xhr_server.coffee
+++ b/test/src/helpers/xhr_server.coffee
@@ -95,6 +95,10 @@ class XhrServer
         response.write json.body if json.body
         response.end()
 
+    # Returns a given URL parameter. Used for URL encoding testing.
+    @app.all '/_/url/:arg', (request, response) =>
+      response.json request.params.arg
+
     # Sends data in small chunks. Used for event testing.
     @app.post '/_/drip', (request, response) ->
       request.connection.setNoDelay()
diff --git a/test/src/xhr_test.coffee b/test/src/xhr_test.coffee
index 0f83657..6e76528 100644
--- a/test/src/xhr_test.coffee
+++ b/test/src/xhr_test.coffee
@@ -70,6 +70,28 @@ describe 'XMLHttpRequest', ->
           done()
         @xhr.send()
 
+    describe 'on an unencoded URL', ->
+      beforeEach ->
+        @xhr.open 'GET', 'http://localhost:8912/_/url/💻'
+
+      it 'encodes correctly', (done) ->
+        @xhr.onload = (event) =>
+          expect(@xhr.status).to.equal 200
+          expect(@xhr.responseText).to.equal '"💻"'
+          done()
+        @xhr.send()
+
+    describe 'on an encoded URL', ->
+      beforeEach ->
+        @xhr.open 'GET', 'http://localhost:8912/_/url/%F0%9F%92%BB'
+
+      it 'does not double-encode', (done) ->
+        @xhr.onload = (event) =>
+          expect(@xhr.status).to.equal 200
+          expect(@xhr.responseText).to.equal '"💻"'
+          done()
+        @xhr.send()
+
   describe 'on a local gopher GET', ->
     describe '#open + #send', ->
       it 'throw a NetworkError', ->