diff --git a/webapp/services/RankActivityService.php b/webapp/services/RankActivityService.php
index dfcfe77f..78667b79 100644
--- a/webapp/services/RankActivityService.php
+++ b/webapp/services/RankActivityService.php
@@ -89,7 +89,7 @@ class RankActivityService extends BaseService {
                      if ($opt == self::OP_SUM) {
                          return "value + ${val}";
                      } else if ($opt == self::OP_GREATEST) {
-                         return "GREATEST(0, ${val})";
+                         return "GREATEST(value, ${val})";
                      } else {
                          return $val;
                      }