diff --git a/index.d.ts b/index.d.ts
index bee86b0..f49d70f 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -12,8 +12,8 @@ declare module 'statsig-node' {
     country?: string;
     locale?: string;
     appVersion?: string;
-    custom?: Record<string, string | number | boolean | Array<string>>;
-    privateAttributes?: Record<string, string | number | boolean | Array<string>>;
+    custom?: Record<string, string | number | boolean | Array<string> | undefined>;
+    privateAttributes?: Record<string, string | number | boolean | Array<string> | undefined>;
   };
 
   /**
diff --git a/src/__tests__/StatsigE2ETest.test.js b/src/__tests__/StatsigE2ETest.test.js
index 17745e2..173464c 100644
--- a/src/__tests__/StatsigE2ETest.test.js
+++ b/src/__tests__/StatsigE2ETest.test.js
@@ -8,6 +8,9 @@ describe('Verify e2e behavior of the SDK with mocked network', () => {
     };
     const randomUser = {
         userID: 'random',
+        privateAttributes: {
+            email: undefined,
+        }
     };
     let postedLogs = {};
     beforeEach(() => {