diff --git a/.travis.yml b/.travis.yml
index 15e3c4e..96f5a18 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -13,7 +13,7 @@ matrix:
   fast_finish: true
 
 before_script:
-  - git clone --depth=50 --branch=master git://github.com/aimeos/aimeos-core.git ../aimeos-core
+  - git clone --depth=50 --branch=2018.04 git://github.com/aimeos/aimeos-core.git ../aimeos-core
   - git clone --depth=50 --branch=master https://github.com/digital-canvas/zend-framework.git ../zendlib
   - cd ../aimeos-core
   - mv ../ai-zend ext/ai-zend
diff --git a/composer.json b/composer.json
index 2121ad7..0bb9140 100644
--- a/composer.json
+++ b/composer.json
@@ -14,7 +14,7 @@
 	"require": {
 		"php": ">=5.3.3",
 		"composer/installers": "^1.0",
-		"aimeos/aimeos-core": "dev-master"
+		"aimeos/aimeos-core": "~2018.04"
 	},
 	"autoload": {
 		"psr-4": {