diff --git a/interface.php b/interface.php
index 8b085da..b27fedc 100644
--- a/interface.php
+++ b/interface.php
@@ -497,18 +497,20 @@ function get_results_by_gameid(ReqHandler &$rh, array $params): array
             global $groupMgr;
             $n = 0;
             foreach ($groups as $groupname) {
-                if ($n > 0) { // place OR between each group criterion
-                    $group_filter[] = "OR";
-                }
                 $group = $groupMgr->getGroupByUniqueName($groupname);
                 if ($group !== null) {
+                    if ($n > 0) { // place OR between each group criterion
+                        $group_filter[] = "OR";
+                    }
+
                     $nicknames = $group->getMembers();
                     $group_filter[] = ["nickname", "IN", $nicknames];
+
+                    $n++;
+                } else { // a group not found means a faulty query
+                    return [];
                 }
-                $n++;
             }
-        } else { // a group not found means a faulty query
-            return [];
         }
 
         // execute filtering