diff --git a/site.mk b/site.mk
index 0f890f7..b07e55c 100644
--- a/site.mk
+++ b/site.mk
@@ -18,7 +18,7 @@ GLUON_SITE_PACKAGES := \
 	haveged
 
 
-DEFAULT_GLUON_RELEASE := 0.4.2
+DEFAULT_GLUON_RELEASE := 0.4.2+0-exp$(shell date '+%Y%m%d')
 
 # Allow overriding the release number from the command line
 GLUON_RELEASE ?= $(DEFAULT_GLUON_RELEASE)