diff --git a/.travis.yml b/.travis.yml
index 9c6cf41..04e4c1e 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -19,7 +19,7 @@ matrix:
     - php: 5.6
       env:
         - DEPS=locked
-        - LEGACY_DEPS="phpunit/phpunit"
+        - LEGACY_DEPS="phpunit/phpunit zendframework/zend-diactoros"
     - php: 5.6
       env:
         - DEPS=latest
@@ -29,7 +29,7 @@ matrix:
     - php: 7
       env:
         - DEPS=locked
-        - LEGACY_DEPS="phpunit/phpunit"
+        - LEGACY_DEPS="phpunit/phpunit zendframework/zend-diactoros"
     - php: 7
       env:
         - DEPS=latest