diff --git a/site.mk b/site.mk
index ed578ee1445b9d23b3199eef5740144f588ab12e..159720f0abeb60fa71257c20f2cd1bd18ea4fbe1 100644
--- a/site.mk
+++ b/site.mk
@@ -34,5 +34,8 @@ GLUON_LANGS := de en
 # Allow overriding the release number from the command line
 GLUON_RELEASE ?= $(DEFAULT_GLUON_RELEASE)
 
+# Region code required for some images; supported values: us eu
+GLUON_REGION ?= eu
+
 # Default priority for updates.
 GLUON_PRIORITY ?= 0.1