diff --git a/deployment/config/build.yaml b/deployment/config/build.yaml
index 0aa4032..61e2d7e 100644
--- a/deployment/config/build.yaml
+++ b/deployment/config/build.yaml
@@ -22,6 +22,7 @@ objects:
       type: Git
       git:
         uri: https://github.com/omallo/ruby-ex
+        ref: master
     strategy:
       type: Source
       sourceStrategy: