diff --git a/src/base-apis.js b/src/base-apis.js
index a86d24465..472e45f51 100644
--- a/src/base-apis.js
+++ b/src/base-apis.js
@@ -255,6 +255,7 @@ MatrixBaseApis.prototype.register = function(
 MatrixBaseApis.prototype.registerGuest = function(opts, callback) {
     opts = opts || {};
     opts.body = opts.body || {};
+    this.setGuest(true);
     return this.registerRequest(opts.body, "guest", callback);
 };