diff --git a/.travis.yml b/.travis.yml
index 90771d521..64da219da 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -289,7 +289,7 @@ sudo: false
 addons:
   apt:
     packages:  # Keep in sync with letsencrypt-auto-source/pieces/bootstrappers/deb_common.sh and Boulder.
-    - python-dev
+    - python3-dev
     - gcc
     - libaugeas0
     - libssl-dev