diff --git a/.travis.yml b/.travis.yml
index 2f6a4b6..d29c9b0 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,5 +1,9 @@
 language: minimal
 
+# Disable git shallow clone. We need full history for validating copyright year of each file.
+git:
+    depth: false
+
 dist: trusty
 
 before_script: