diff --git a/.travis.yml b/.travis.yml
index a833924..149735f 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -130,7 +130,7 @@ requires:
     - yelp-tools
 
 variables:
-  - CFLAGS="-Wall -Werror=format-security"
+  - CFLAGS="-Wall -Werror=format-security -Wredundant-decls"
   - 'CHECKERS="
     -enable-checker deadcode.DeadStores
     -enable-checker alpha.deadcode.UnreachableCode