diff --git a/app/models/value_group.rb b/app/models/value_group.rb
index 0e65779d..707f8a26 100644
--- a/app/models/value_group.rb
+++ b/app/models/value_group.rb
@@ -40,7 +40,8 @@
     end
 
     def percent_of_total
-        return 100 if parent.nil?
+        return 100 if parent.nil? || parent.sum.zero?
+
         ((sum / parent.sum) * 100).round(1)
     end