diff --git a/packages/basic.gblib/services/SystemKeywords.ts b/packages/basic.gblib/services/SystemKeywords.ts
index 1815bfd3..5f842e8b 100644
--- a/packages/basic.gblib/services/SystemKeywords.ts
+++ b/packages/basic.gblib/services/SystemKeywords.ts
@@ -411,12 +411,12 @@ export class SystemKeywords {
                 }
                 break;
               case 'not in':
-                if (filter.value.indexOf(result)) {
+                if (filter.value.indexOf(result) === -1) {
                   filterAcceptCount++;
                 }
                 break;
               case 'in':
-                if (!filter.value.indexOf(result)) {
+                if (filter.value.indexOf(result) !== -1) {
                   filterAcceptCount++;
                 }
                 break;