diff --git a/build.xml b/build.xml
index 63aa46d..a0440d5 100644
--- a/build.xml
+++ b/build.xml
@@ -109,10 +109,10 @@
     -->
 
     <!-- Default validUntil duration for all generated metadata, in days. -->
-    <property name="validUntil.default.days" value="14"/>
+    <property name="validUntil.default.days" value="21"/>
 
     <!-- Specific validUntil duration for aggregates, in days. -->
-    <property name="validUntil.aggregate.days" value="21"/>
+    <property name="validUntil.aggregate.days" value="${validUntil.default.days}"/>
     <!-- Same value, as an ISO 8601 duration. -->
     <property name="validUntil.aggregate.duration" value="P${validUntil.aggregate.days}D"/>