diff --git a/.travis.yml b/.travis.yml
index e493c534..43c931da 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -8,8 +8,14 @@ cache:
 git:
   depth: false
 
+addons:
+  apt:
+    packages:
+      - tree
+
 before_install:
   - date
+  - tree
 
 install:
   - pip install poetry~=0.12.17