diff --git a/web/src/people.js b/web/src/people.js
index fe977ed491..24da8bb5df 100644
--- a/web/src/people.js
+++ b/web/src/people.js
@@ -943,7 +943,7 @@ export function get_non_active_realm_users() {
 export function is_cross_realm_email(email) {
     const person = get_by_email(email);
     if (!person) {
-        return undefined;
+        return false;
     }
     return cross_realm_dict.has(person.user_id);
 }
diff --git a/web/tests/people.test.js b/web/tests/people.test.js
index 020b4ea4dc..336783318f 100644
--- a/web/tests/people.test.js
+++ b/web/tests/people.test.js
@@ -352,7 +352,7 @@ test_people("basics", () => {
     assert.equal(person.full_name, "Me Myself");
 
     // Test undefined people
-    assert.equal(people.is_cross_realm_email("unknown@example.com"), undefined);
+    assert.equal(people.is_cross_realm_email("unknown@example.com"), false);
 
     // Test is_my_user_id function
     assert.equal(people.is_my_user_id(me.user_id), true);