diff --git a/index.js b/index.js
index 88159f0..f1a918b 100644
--- a/index.js
+++ b/index.js
@@ -34,9 +34,9 @@
         'duomobile.s3-us-west-1.amazonaws.com'
     ];
 
-    var iframeId = 'duo_iframe',
-        postAction = '',
-        postArgument = 'sig_response',
+    var iframeId,
+        postAction,
+        postArgument,
         host,
         sigRequest,
         duoSig,
@@ -44,6 +44,26 @@
         iframe,
         submitCallback;
 
+    // We use this function instead of setting initial values in the var
+    // declarations to make sure the initial values and subsequent
+    // re-initializations are always the same.
+    initializeStatefulVariables();
+
+    /**
+     * Set local variables to whatever they should be before you call init().
+     */
+    function initializeStatefulVariables() {
+        iframeId = 'duo_iframe';
+        postAction = '';
+        postArgument = 'sig_response';
+        host = undefined;
+        sigRequest = undefined;
+        duoSig = undefined;
+        appSig = undefined;
+        iframe = undefined;
+        submitCallback = undefined;
+    }
+
     function throwError(message, url) {
         throw new Error(
             'Duo Web SDK error: ' + message +
@@ -225,6 +245,12 @@
      *                                                        submit_callback can be used to prevent the webpage from reloading.
      */
     function init(options) {
+        // If init() is called more than once we have to reset all the local
+        // variables to ensure init() will work the same way every time. This
+        // helps people making single page applications. SPAs may periodically
+        // remove the iframe and add a new one that has to be initialized.
+        initializeStatefulVariables();
+
         if (options) {
             if (options.host) {
                 host = options.host;
@@ -375,7 +401,7 @@
         iframe.src = [
             'https://', host, '/frame/web/v1/auth?tx=', duoSig,
             '&parent=', encodeURIComponent(document.location.href),
-            '&v=2.6'
+            '&v=2.7'
         ].join('');
 
         // listen for the 'message' event
diff --git a/package.json b/package.json
index 3b9163b..373bbbd 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "duo_web_sdk",
-  "version": "2.6.0",
+  "version": "2.7.0",
   "description": "Provides the Duo Web Javascript in an ES6 module format that can be installed via npm and bundled into your web application.",
   "main": "index.js",
   "dependencies": {},
diff --git a/test/test-duo-web.js b/test/test-duo-web.js
index 277fc5f..b8f3601 100644
--- a/test/test-duo-web.js
+++ b/test/test-duo-web.js
@@ -9,13 +9,17 @@ describe('Duo Web', function() {
          /* Dummy sig_request, passes validation. */
         var sig_request = 'AUTH|duo_sig:app_sig';
 
-        beforeEach(function() {
+        function addIframe() {
             /* Create some document elements that doPostBack expects. */
             iframe = document.createElement('iframe');
             var form = document.createElement('duo_form');
             form.id = 'duo_form';
             document.head.appendChild(iframe);
             iframe.appendChild(form);
+        }
+
+        beforeEach(function() {
+            addIframe();
         });
 
         it('Should totes work with submitCallback', function() {
@@ -34,6 +38,18 @@ describe('Duo Web', function() {
             assert.isTrue(submitCallbackCalled);
         });
 
+        it('should include the host in the src', function() {
+            var host = 'this-is-a-host.example';
+
+            Duo.init({
+                host: host,
+                iframe: iframe,
+                sig_request: sig_request
+            });
+
+            assert.include(iframe.src, host);
+        });
+
         it('should URI encode the parent URL', function() {
             Duo.init({
                 host: 'example.com',
@@ -48,6 +64,82 @@ describe('Duo Web', function() {
                 iframe.src, 'parent=https://',
                 'should URI encode the parent href')
         })
+
+        describe('Calling init() a second time', function() {
+            it('Should overwrite the old callback', function() {
+                var firstSubmitCallbackCalled = false;
+                var secondSubmitCallbackCalled = false;
+
+                Duo.init({
+                    host: 'example.com',
+                    iframe: iframe,
+                    sig_request: sig_request,
+                    submit_callback: function() {
+                        firstSubmitCallbackCalled = true;
+                    }
+                });
+
+                Duo.init({
+                    host: 'example.com',
+                    iframe: iframe,
+                    sig_request: sig_request,
+                    submit_callback: function() {
+                        secondSubmitCallbackCalled = true;
+                    }
+                });
+
+                Duo._doPostBack("Great Success!");
+
+                assert.isFalse(
+                    firstSubmitCallbackCalled,
+                    'did not overwrite the previous callback'
+                );
+                assert.isTrue(
+                    secondSubmitCallbackCalled,
+                    'did not call the new callback'
+                );
+            });
+
+            it('Should overwrite the iframe src', function() {
+                const firstHostName = 'first-host.example';
+                const secondHostName = 'second-host.example';
+                const thirdHostName = 'third-host.example';
+
+                // Initialize with one host
+                Duo.init({
+                    host: firstHostName,
+                    iframe: iframe,
+                    sig_request: sig_request
+                });
+
+                // Initialize with a different host
+                Duo.init({
+                    host: secondHostName,
+                    iframe: iframe,
+                    sig_request: sig_request
+                });
+
+                assert.include(
+                    iframe.src, secondHostName,
+                    'did not change the src on the second init'
+                );
+
+
+                // Create a new iframe and initialze again to make sure the new
+                // iframe is targeted.
+                addIframe();
+                Duo.init({
+                    host: thirdHostName,
+                    iframe: iframe,
+                    sig_request: sig_request
+                });
+
+                assert.include(
+                    iframe.src, thirdHostName,
+                    'did not change the src on the third init'
+                );
+            });
+        });
     });
 
     describe('parseSigRequest', function() {