diff --git a/site.mk b/site.mk
index f2b5db07240f92ceb7239601f4188291f7446b30..276b73a49a80127ef251889ebec4a1e4428bdfe7 100644
--- a/site.mk
+++ b/site.mk
@@ -45,7 +45,7 @@ GLUON_SITE_PACKAGES += \
 	kmod-igb
 endif
 
-DEFAULT_GLUON_RELEASE := 0.9+$(shell date '+%Y.%m.%d')-g.$(shell git -C $(GLUONDIR) log --pretty=format:'%h' -n 1)-s.$(shell git -C $(GLUONDIR)/site log --pretty=format:'%h' -n 1)
+DEFAULT_GLUON_RELEASE := 0.9+$(shell date '+%Y-%m-%d')-g.$(shell git -C $(GLUONDIR) log --pretty=format:'%h' -n 1)-s.$(shell git -C $(GLUONDIR)/site log --pretty=format:'%h' -n 1)
 
 GLUON_LANGS := de en