diff --git a/ts/src/header-validator/trigger.test.ts b/ts/src/header-validator/trigger.test.ts
index ee727ae740..8c1f70d49f 100644
--- a/ts/src/header-validator/trigger.test.ts
+++ b/ts/src/header-validator/trigger.test.ts
@@ -169,6 +169,18 @@ const testCases: jsontest.TestCase<Trigger>[] = [
       ]
     }`,
   },
+  {
+    name: 'missing-optional-filtering-id',
+    json: `{
+      "aggregatable_trigger_data": [{
+        "key_piece": "0x1",
+        "source_keys": ["a"]
+      }],
+      "aggregatable_values": {
+        "a": { "value": 3 }
+      }
+    }`,
+  },
   {
     name: 'or-filters',
     json: `{
diff --git a/ts/src/header-validator/validate-json.ts b/ts/src/header-validator/validate-json.ts
index 9cfc5164f8..12ce80dedc 100644
--- a/ts/src/header-validator/validate-json.ts
+++ b/ts/src/header-validator/validate-json.ts
@@ -1226,8 +1226,10 @@ function aggregatableKeyValue(
     object: (j) =>
       struct(j, ctx, {
         value: field('value', aggregatableKeyValueValue),
-        filteringId: field('filtering_id', (j) =>
-          aggregatableKeyValueFilteringId(j, ctx, maxBytes)
+        filteringId: field(
+          'filtering_id',
+          (j) => aggregatableKeyValueFilteringId(j, ctx, maxBytes),
+          0n
         ),
       }),
   })