diff --git a/.travis.yml b/.travis.yml
index db64272db7..e53e611bf8 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -440,9 +440,7 @@ script:
 # Branch matrix.  Not all branches are Travis-ready so we limit branches here.
 branches:
   only:
-    # Because default branch is still "trunk", we build only "trunk" to avoid
-    # doubly building on master and trigger CI on Pull Request.
-    - trunk # TODO: s/master/trunk/ when the default branch is switched to master on 7/1.
+    - master
     - ruby_2_4
     - ruby_2_5
     - ruby_2_6