diff --git a/src/components/structures/auth/Registration.js b/src/components/structures/auth/Registration.js
index 6b578f0f68..04570df868 100644
--- a/src/components/structures/auth/Registration.js
+++ b/src/components/structures/auth/Registration.js
@@ -94,7 +94,7 @@ module.exports = React.createClass({
             // If we've been given a session ID, we're resuming
             // straight back into UI auth
             doingUIAuth: Boolean(this.props.sessionId),
-            serverType: null,
+            serverType: ServerType.getTypeFromHsUrl(this.props.customHsUrl),
             hsUrl: this.props.customHsUrl,
             isUrl: this.props.customIsUrl,
             // Phase of the overall registration dialog.
@@ -122,7 +122,7 @@ module.exports = React.createClass({
         });
     },
 
-    onServerTypeChange(type, initial) {
+    onServerTypeChange(type) {
         this.setState({
             serverType: type,
         });
@@ -148,15 +148,10 @@ module.exports = React.createClass({
                     hsUrl: this.props.defaultHsUrl,
                     isUrl: this.props.defaultIsUrl,
                 });
-                // if this is the initial value from the control and we're
-                // already in the registration phase, don't go back to the
-                // server details phase (but do if it's actually a change resulting
-                // from user interaction).
-                if (!initial || !this.state.phase === PHASE_REGISTRATION) {
-                    this.setState({
-                        phase: PHASE_SERVER_DETAILS,
-                    });
-                }
+                // Reset back to server details on type change.
+                this.setState({
+                    phase: PHASE_SERVER_DETAILS,
+                });
                 break;
         }
     },
@@ -389,12 +384,9 @@ module.exports = React.createClass({
         // If we're on a different phase, we only show the server type selector,
         // which is always shown if we allow custom URLs at all.
         if (PHASES_ENABLED && this.state.phase !== PHASE_SERVER_DETAILS) {
-            // if we've been given a custom HS URL we should actually pass that, so
-            // that the appropriate section is selected at the start to match the
-            // homeserver URL we're using
             return <div>
                 <ServerTypeSelector
-                    defaultHsUrl={this.props.customHsUrl || this.props.defaultHsUrl}
+                    selected={this.state.serverType}
                     onChange={this.onServerTypeChange}
                 />
             </div>;
@@ -436,7 +428,7 @@ module.exports = React.createClass({
 
         return <div>
             <ServerTypeSelector
-                defaultHsUrl={this.props.defaultHsUrl}
+                selected={this.state.serverType}
                 onChange={this.onServerTypeChange}
             />
             {serverDetails}
diff --git a/src/components/views/auth/ServerTypeSelector.js b/src/components/views/auth/ServerTypeSelector.js
index 25f5dcee66..a9311acd7b 100644
--- a/src/components/views/auth/ServerTypeSelector.js
+++ b/src/components/views/auth/ServerTypeSelector.js
@@ -56,12 +56,12 @@ export const TYPES = {
     },
 };
 
-function getDefaultType(defaultHsUrl) {
-    if (!defaultHsUrl) {
+export function getTypeFromHsUrl(hsUrl) {
+    if (!hsUrl) {
         return null;
-    } else if (defaultHsUrl === TYPES.FREE.hsUrl) {
+    } else if (hsUrl === TYPES.FREE.hsUrl) {
         return FREE;
-    } else if (new URL(defaultHsUrl).hostname.endsWith('.modular.im')) {
+    } else if (new URL(hsUrl).hostname.endsWith('.modular.im')) {
         // This is an unlikely case to reach, as Modular defaults to hiding the
         // server type selector.
         return PREMIUM;
@@ -72,8 +72,8 @@ function getDefaultType(defaultHsUrl) {
 
 export default class ServerTypeSelector extends React.PureComponent {
     static propTypes = {
-        // The default HS URL as another way to set the initially selected type.
-        defaultHsUrl: PropTypes.string,
+        // The default selected type.
+        selected: PropTypes.string,
         // Handler called when the selected type changes.
         onChange: PropTypes.func.isRequired,
     }
@@ -82,20 +82,12 @@ export default class ServerTypeSelector extends React.PureComponent {
         super(props);
 
         const {
-            defaultHsUrl,
-            onChange,
+            selected,
         } = props;
-        const type = getDefaultType(defaultHsUrl);
+
         this.state = {
-            selected: type,
+            selected,
         };
-        if (onChange) {
-            // FIXME: Supply a second 'initial' param here to flag that this is
-            // initialising the value rather than from user interaction
-            // (which sometimes we'll want to ignore). Must be a better way
-            // to do this.
-            onChange(type, true);
-        }
     }
 
     updateSelectedType(type) {