diff --git a/lib/www/server/lib/comparisons/geometric-differences.js b/lib/www/server/lib/comparisons/geometric-differences.js
index 7e3242b..79b5ff3 100644
--- a/lib/www/server/lib/comparisons/geometric-differences.js
+++ b/lib/www/server/lib/comparisons/geometric-differences.js
@@ -332,7 +332,7 @@ async function getGroup (groupName, opts = {}) {
 
 	const group = (await groups())?.[groupName]?.map( i => i.pid)?.sort();
 
-	if (!group?.length) return;
+	if (!group?.length || group?.length < 2) return;
 
 	const client = await pool.connect();