diff --git a/src/components/structures/login/Login.js b/src/components/structures/login/Login.js
index 67d9bb7d38..fae7cc37df 100644
--- a/src/components/structures/login/Login.js
+++ b/src/components/structures/login/Login.js
@@ -232,11 +232,24 @@ module.exports = React.createClass({
         }).done();
     },
 
-    onUsernameChanged: function(username, endOfInput) {
+    onUsernameChanged: function(username) {
         this.setState({ username: username });
-        if (username[0] === "@" && endOfInput) {
+    },
+
+    onUsernameBlur: function(username) {
+        this.setState({ username: username });
+        if (username[0] === "@") {
             const serverName = username.split(':').slice(1).join(':');
-            this._tryWellKnownDiscovery(serverName);
+            try {
+                // we have to append 'https://' to make the URL constructor happy
+                // otherwise we get things like 'protocol: matrix.org, pathname: 8448'
+                const url = new URL("https://" + serverName);
+                this._tryWellKnownDiscovery(url.hostname);
+            } catch (e) {
+                console.error("Problem parsing URL or unhandled error doing .well-known discovery");
+                console.error(e);
+                this.setState({discoveryError: _t("Failed to perform homeserver discovery")});
+            }
         }
     },
 
@@ -531,6 +544,7 @@ module.exports = React.createClass({
                initialPhoneCountry={this.state.phoneCountry}
                initialPhoneNumber={this.state.phoneNumber}
                onUsernameChanged={this.onUsernameChanged}
+               onUsernameBlur={this.onUsernameBlur}
                onPhoneCountryChanged={this.onPhoneCountryChanged}
                onPhoneNumberChanged={this.onPhoneNumberChanged}
                onForgotPasswordClick={this.props.onForgotPasswordClick}
diff --git a/src/components/views/login/PasswordLogin.js b/src/components/views/login/PasswordLogin.js
index 0e3aed1187..6a5577fb62 100644
--- a/src/components/views/login/PasswordLogin.js
+++ b/src/components/views/login/PasswordLogin.js
@@ -30,6 +30,7 @@ class PasswordLogin extends React.Component {
     static defaultProps = {
         onError: function() {},
         onUsernameChanged: function() {},
+        onUsernameBlur: function() {},
         onPasswordChanged: function() {},
         onPhoneCountryChanged: function() {},
         onPhoneNumberChanged: function() {},
@@ -122,11 +123,11 @@ class PasswordLogin extends React.Component {
 
     onUsernameChanged(ev) {
         this.setState({username: ev.target.value});
-        this.props.onUsernameChanged(ev.target.value, false);
+        this.props.onUsernameChanged(ev.target.value);
     }
 
     onUsernameBlur(ev) {
-        this.props.onUsernameChanged(this.state.username, true);
+        this.props.onUsernameBlur(this.state.username);
     }
 
     onLoginTypeChange(loginType) {
diff --git a/src/i18n/strings/en_EN.json b/src/i18n/strings/en_EN.json
index eb0a7fb1db..f9980f5645 100644
--- a/src/i18n/strings/en_EN.json
+++ b/src/i18n/strings/en_EN.json
@@ -1288,6 +1288,7 @@
     "Incorrect username and/or password.": "Incorrect username and/or password.",
     "Please note you are logging into the %(hs)s server, not matrix.org.": "Please note you are logging into the %(hs)s server, not matrix.org.",
     "Guest access is disabled on this Home Server.": "Guest access is disabled on this Home Server.",
+    "Failed to perform homeserver discovery": "Failed to perform homeserver discovery",
     "The phone number entered looks invalid": "The phone number entered looks invalid",
     "Invalid homeserver discovery response": "Invalid homeserver discovery response",
     "Cannot find homeserver": "Cannot find homeserver",