diff --git a/.travis.yml b/.travis.yml
index 19c7d2df3..1d1ac415b 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -15,9 +15,10 @@ env:
     - IS_PULL_REQUEST=$TRAVIS_PULL_REQUEST
     - BUILD_DIR=$TRAVIS_BUILD_DIR
     - DRUPAL_CORE_HEAD=8.5.x-dev
+    - DRUPAL_CORE_STABLE=8.5.6
   matrix:
-    - DRUPAL_CORE_VERSION=default PHPUNIT_EXCLUDE_GROUP='long,requires-vm'
-    - DRUPAL_CORE_VERSION=default PHPUNIT_GROUP='long' PHPUNIT_EXCLUDE_GROUP='requires-vm'
+    - DRUPAL_CORE_VERSION=$DRUPAL_CORE_STABLE PHPUNIT_EXCLUDE_GROUP='long,requires-vm'
+    - DRUPAL_CORE_VERSION=$DRUPAL_CORE_STABLE PHPUNIT_GROUP='long' PHPUNIT_EXCLUDE_GROUP='requires-vm'
     - DRUPAL_CORE_VERSION=$DRUPAL_CORE_HEAD
 
 matrix:
diff --git a/composer.required.json b/composer.required.json
index 5e2b6b17c..0a6cfc1df 100644
--- a/composer.required.json
+++ b/composer.required.json
@@ -6,7 +6,7 @@
     }
   },
   "require": {
-    "drupal/core": "^8.5.6",
+    "drupal/core": "8.5.*",
     "drupal/config_split": "^1.0.0"
   },
   "require-dev": {