diff --git a/.travis.yml b/.travis.yml
index db2206bfe..3ce7d53ed 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -15,6 +15,7 @@ addons:
             - libc-ares-dev
             - g++-4.8
             - libstdc++-4.8-dev
+            - stunnel4
 
 matrix:
     include: