diff --git a/lib/interfaces/common.js b/lib/interfaces/common.js
index e7e84b2511..53c8d8c26c 100644
--- a/lib/interfaces/common.js
+++ b/lib/interfaces/common.js
@@ -93,6 +93,9 @@ module.exports = function(suites, context, mocha) {
        * @returns {Suite}
        */
       only: function only(opts) {
+        if (mocha.options.forbidOnly) {
+          throw createUnsupportedError('`.only` forbidden');
+        }
         opts.isOnly = true;
         return this.create(opts);
       },
@@ -126,11 +129,7 @@ module.exports = function(suites, context, mocha) {
         suite.file = opts.file;
         suites.unshift(suite);
         if (opts.isOnly) {
-          if (mocha.options.forbidOnly && shouldBeTested(suite)) {
-            throw createUnsupportedError('`.only` forbidden');
-          }
-
-          suite.parent.appendOnlySuite(suite);
+          suite.markOnly();
         }
         if (suite.pending) {
           if (mocha.options.forbidPending && shouldBeTested(suite)) {