diff --git a/src/components/views/settings/AddPhoneNumber.js b/src/components/views/settings/AddPhoneNumber.js
index 9680bdd12d..bb5ecd2694 100644
--- a/src/components/views/settings/AddPhoneNumber.js
+++ b/src/components/views/settings/AddPhoneNumber.js
@@ -116,6 +116,7 @@ export default WithMatrixClient(React.createClass({
                     this._addThreepid = null;
                     return;
                 }
+                if (this._unmounted) return;
                 this.setState({msisdn_add_pending: true});
                 this._addThreepid.haveMsisdnToken(token).then(() => {
                     this._addThreepid = null;