diff --git a/src/root/build.tt b/src/root/build.tt
index 11dd1b92..061e4afe 100644
--- a/src/root/build.tt
+++ b/src/root/build.tt
@@ -7,7 +7,7 @@
 [% project = build.project %]
 [% jobset = build.jobset %]
 [% job = build.job %]
-[% isAggregate = constituents ? 1 : 0 %]
+[% isAggregate = constituents.size > 0 %]
 
 [% BLOCK renderOutputs %]
   [% start=1; FOREACH output IN outputs %]