diff --git a/sdk_container/src/third_party/coreos-overlay/profiles/coreos/base/make.defaults b/sdk_container/src/third_party/coreos-overlay/profiles/coreos/base/make.defaults
index d775af9b65..623d494da7 100644
--- a/sdk_container/src/third_party/coreos-overlay/profiles/coreos/base/make.defaults
+++ b/sdk_container/src/third_party/coreos-overlay/profiles/coreos/base/make.defaults
@@ -71,7 +71,7 @@ CCACHE_SIZE="2.5G"
 
 # Always build binary packages, remove old build logs, avoid running as root.
 FEATURES="buildpkg ccache clean-logs compressdebug parallel-install splitdebug
-          userfetch userpriv usersandbox"
+          userfetch userpriv usersandbox -merge-sync"
 
 # No need to restrict access to build directories in dev environments.
 PORTAGE_WORKDIR_MODE="0755"