diff --git a/inventory/builders b/inventory/builders
index 917916dc33..16f6c4ad33 100644
--- a/inventory/builders
+++ b/inventory/builders
@@ -277,8 +277,7 @@ arm04-builder16.arm.fedoraproject.org
 arm04-builder18.arm.fedoraproject.org
 arm04-builder19.arm.fedoraproject.org
 arm04-builder20.arm.fedoraproject.org
-# disappeared from chassis 20160718
-#arm04-builder21.arm.fedoraproject.org
+arm04-builder21.arm.fedoraproject.org
 arm04-builder22.arm.fedoraproject.org
 arm04-builder23.arm.fedoraproject.org