diff --git a/src/services/evaluator.ts b/src/services/evaluator.ts
index 0b38395..4623363 100644
--- a/src/services/evaluator.ts
+++ b/src/services/evaluator.ts
@@ -111,7 +111,7 @@ export class Evaluator {
 
     // If the criteria object does not have the field
     // we are looking for, we should return false.
-    if (!criterion) {
+    if (undefined === criterion) {
       return false;
     }