diff --git a/.travis.yml b/.travis.yml
index 967ce1b..9b057fd 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -7,6 +7,9 @@ elixir:
   - 1.9
   - 1.10
   - 1.11
+otp_release:
+  - '20'
+  - '21'
 sudo: false
 before_script:
   - mix deps.get --only test