diff --git a/res/css/views/auth/_AuthBody.scss b/res/css/views/auth/_AuthBody.scss
index 6216bdd4b8..778f5f6a4d 100644
--- a/res/css/views/auth/_AuthBody.scss
+++ b/res/css/views/auth/_AuthBody.scss
@@ -58,6 +58,10 @@ limitations under the License.
     background-color: $authpage-body-bg-color;
 }
 
+.mx_AuthBody input.error {
+    color: $warning-color;
+}
+
 .mx_AuthBody_editServerDetails {
     padding-left: 1em;
     font-size: 12px;
diff --git a/src/components/structures/auth/Registration.js b/src/components/structures/auth/Registration.js
index 711ec3c1d7..1fcaa77d54 100644
--- a/src/components/structures/auth/Registration.js
+++ b/src/components/structures/auth/Registration.js
@@ -308,7 +308,19 @@ module.exports = React.createClass({
         });
     },
 
-    onFormValidationFailed: function(errCode) {
+    onFormValidationChange: function(fieldErrors) {
+        // `fieldErrors` is an object mapping field IDs to error codes when there is an
+        // error or `null` for no error, so the values array will be something like:
+        // `[ null, "RegistrationForm.ERR_PASSWORD_MISSING", null]`
+        // Find the first non-null error code and show that.
+        const errCode = Object.values(fieldErrors).find(value => !!value);
+        if (!errCode) {
+            this.setState({
+                errorText: null,
+            });
+            return;
+        }
+
         let errMsg;
         switch (errCode) {
             case "RegistrationForm.ERR_PASSWORD_MISSING":
@@ -510,7 +522,7 @@ module.exports = React.createClass({
                 defaultPhoneNumber={this.state.formVals.phoneNumber}
                 defaultPassword={this.state.formVals.password}
                 minPasswordLength={MIN_PASSWORD_LENGTH}
-                onError={this.onFormValidationFailed}
+                onValidationChange={this.onFormValidationChange}
                 onRegisterClick={this.onFormSubmit}
                 onEditServerDetailsClick={onEditServerDetailsClick}
                 flows={this.state.flows}
diff --git a/src/components/views/auth/RegistrationForm.js b/src/components/views/auth/RegistrationForm.js
index eabdcd0dd2..d031dc7bdd 100644
--- a/src/components/views/auth/RegistrationForm.js
+++ b/src/components/views/auth/RegistrationForm.js
@@ -46,7 +46,7 @@ module.exports = React.createClass({
         defaultUsername: PropTypes.string,
         defaultPassword: PropTypes.string,
         minPasswordLength: PropTypes.number,
-        onError: PropTypes.func,
+        onValidationChange: PropTypes.func,
         onRegisterClick: PropTypes.func.isRequired, // onRegisterClick(Object) => ?Promise
         onEditServerDetailsClick: PropTypes.func,
         flows: PropTypes.arrayOf(PropTypes.object).isRequired,
@@ -60,15 +60,14 @@ module.exports = React.createClass({
     getDefaultProps: function() {
         return {
             minPasswordLength: 6,
-            onError: function(e) {
-                console.error(e);
-            },
+            onValidationChange: console.error,
         };
     },
 
     getInitialState: function() {
         return {
-            fieldValid: {},
+            // Field error codes by field ID
+            fieldErrors: {},
             // The ISO2 country code selected in the phone number entry
             phoneCountry: this.props.defaultPhoneCountry,
         };
@@ -81,12 +80,12 @@ module.exports = React.createClass({
         // the error that ends up being displayed
         // is the one from the first invalid field.
         // It's not super ideal that this just calls
-        // onError once for each invalid field.
+        // onValidationChange once for each invalid field.
+        this.validateField(FIELD_PHONE_NUMBER, ev.type);
+        this.validateField(FIELD_EMAIL, ev.type);
         this.validateField(FIELD_PASSWORD_CONFIRM, ev.type);
         this.validateField(FIELD_PASSWORD, ev.type);
         this.validateField(FIELD_USERNAME, ev.type);
-        this.validateField(FIELD_PHONE_NUMBER, ev.type);
-        this.validateField(FIELD_EMAIL, ev.type);
 
         const self = this;
         if (this.allFieldsValid()) {
@@ -134,9 +133,9 @@ module.exports = React.createClass({
      * @returns {boolean} true if all fields were valid last time they were validated.
      */
     allFieldsValid: function() {
-        const keys = Object.keys(this.state.fieldValid);
+        const keys = Object.keys(this.state.fieldErrors);
         for (let i = 0; i < keys.length; ++i) {
-            if (this.state.fieldValid[keys[i]] == false) {
+            if (this.state.fieldErrors[keys[i]]) {
                 return false;
             }
         }
@@ -206,21 +205,29 @@ module.exports = React.createClass({
                 }
                 break;
             case FIELD_PASSWORD_CONFIRM:
-                this.markFieldValid(
-                    fieldID, pwd1 == pwd2,
-                    "RegistrationForm.ERR_PASSWORD_MISMATCH",
-                );
+                if (allowEmpty && pwd2 === "") {
+                    this.markFieldValid(fieldID, true);
+                } else {
+                    this.markFieldValid(
+                        fieldID, pwd1 == pwd2,
+                        "RegistrationForm.ERR_PASSWORD_MISMATCH",
+                    );
+                }
                 break;
         }
     },
 
-    markFieldValid: function(fieldID, val, errorCode) {
-        const fieldValid = this.state.fieldValid;
-        fieldValid[fieldID] = val;
-        this.setState({fieldValid: fieldValid});
-        if (!val) {
-            this.props.onError(errorCode);
+    markFieldValid: function(fieldID, valid, errorCode) {
+        const { fieldErrors } = this.state;
+        if (valid) {
+            fieldErrors[fieldID] = null;
+        } else {
+            fieldErrors[fieldID] = errorCode;
         }
+        this.setState({
+            fieldErrors,
+        });
+        this.props.onValidationChange(fieldErrors);
     },
 
     fieldElementById(fieldID) {
@@ -240,7 +247,7 @@ module.exports = React.createClass({
 
     _classForField: function(fieldID, ...baseClasses) {
         let cls = baseClasses.join(' ');
-        if (this.state.fieldValid[fieldID] === false) {
+        if (this.state.fieldErrors[fieldID]) {
             if (cls) cls += ' ';
             cls += 'error';
         }