diff --git a/src/users/__tests__/usersReducer-test.js b/src/users/__tests__/usersReducer-test.js
index 3c04721b531..6c6e53ab580 100644
--- a/src/users/__tests__/usersReducer-test.js
+++ b/src/users/__tests__/usersReducer-test.js
@@ -5,6 +5,7 @@ import * as eg from '../../__tests__/lib/exampleData';
 import { UploadedAvatarURL } from '../../utils/avatar';
 import { EVENT_USER_ADD, ACCOUNT_SWITCH, EVENT } from '../../actionConstants';
 import { EventTypes, type RealmUserUpdateEvent } from '../../api/eventTypes';
+import type { User } from '../../types';
 import { RoleValues } from '../../api/permissionsTypes';
 import usersReducer from '../usersReducer';
 import { randString } from '../../utils/misc';
@@ -54,12 +55,22 @@ describe('usersReducer', () => {
      * Check that an update event with supplied `person` works.
      *
      * May omit `user_id` to avoid repetition.
+     *
+     * Normally, the expected User value after the change is
+     *
+     *   { ...theUser, ...person }
+     *
+     * But in at least one case (when updating custom profile fields), that
+     * isn't even a valid User object because `person`'s properties aren't
+     * a subset of User's. To handle that, callers can pass an
+     * `expectedUser`.
      */
     // Tell ESLint to recognize `check` as a helper function that runs
     // assertions.
     /* eslint jest/expect-expect: ["error", { "assertFunctionNames": ["expect", "check"] }] */
     const check = <P: $PropertyType<RealmUserUpdateEvent, 'person'>>(
       personMaybeWithoutId: $Rest<P, {| user_id?: mixed |}>,
+      expectedUser?: User,
     ) => {
       const person: P = { user_id: theUser.user_id, ...personMaybeWithoutId };
 
@@ -68,7 +79,7 @@ describe('usersReducer', () => {
         event: { id: 1, type: EventTypes.realm_user, op: 'update', person },
       });
 
-      expect(usersReducer(prevState, action)).toEqual([{ ...theUser, ...person }]);
+      expect(usersReducer(prevState, action)).toEqual([expectedUser ?? { ...theUser, ...person }]);
     };
 
     /*
@@ -79,7 +90,7 @@ describe('usersReducer', () => {
      * A few properties that we don't handle are commented out.
      */
 
-    test.skip('When a user changes their full name.', () => {
+    test('When a user changes their full name.', () => {
       check({ full_name: randString() });
     });
 
@@ -95,34 +106,38 @@ describe('usersReducer', () => {
       });
     });
 
-    test.skip('When a user changes their timezone setting.', () => {
+    test('When a user changes their timezone setting.', () => {
       check({ timezone: randString() });
     });
 
-    test.skip('When the owner of a bot changes.', () => {
-      check({ user_id: theUser.user_id, bot_owner_id: (theUser.bot_owner_id ?? 1) + 1 });
+    test('When the owner of a bot changes.', () => {
+      check({ bot_owner_id: (theUser.bot_owner_id ?? 1) + 1 });
     });
 
     test('When the role of a user changes.', () => {
       check({ role: RoleValues[(RoleValues.indexOf(theUser.role) + 1) % RoleValues.length] });
     });
 
-    test.skip("When a user's billing-admin status changes", () => {
-      check({ user_id: theUser.user_id, is_billing_admin: !theUser.is_billing_admin });
+    test("When a user's billing-admin status changes", () => {
+      check({ is_billing_admin: !theUser.is_billing_admin });
     });
 
-    test.skip('When the delivery email of a user changes.', () => {
+    test('When the delivery email of a user changes.', () => {
       check({ delivery_email: randString() });
     });
 
-    test.skip('When the user updates one of their custom profile fields.', () => {
-      check({
-        custom_profile_field: { id: 4, value: randString(), rendered_value: randString() },
-      });
+    test('When the user updates one of their custom profile fields.', () => {
+      const value = randString();
+      const rendered_value = randString();
+      check(
+        { custom_profile_field: { id: 4, value, rendered_value } },
+        { ...theUser, profile_data: { '4': { value, rendered_value } } },
+      );
     });
 
-    test.skip('When the Zulip display email address of a user changes', () => {
-      check({ user_id: theUser.user_id, new_email: randString() });
+    test('When the Zulip display email address of a user changes', () => {
+      const new_email = randString();
+      check({ user_id: theUser.user_id, new_email }, { ...theUser, email: new_email });
     });
   });
 
diff --git a/src/users/usersReducer.js b/src/users/usersReducer.js
index 4312c57c15d..9da8a9dd55c 100644
--- a/src/users/usersReducer.js
+++ b/src/users/usersReducer.js
@@ -1,5 +1,5 @@
 /* @flow strict-local */
-import type { UsersState, PerAccountApplicableAction } from '../types';
+import type { User, UsersState, PerAccountApplicableAction } from '../types';
 import {
   LOGOUT,
   LOGIN_SUCCESS,
@@ -40,13 +40,25 @@ export default (
           switch (event.op) {
             case 'update': {
               return state.map(user => {
-                if (user.user_id !== event.person.user_id) {
+                const { person } = event;
+                if (user.user_id !== person.user_id) {
                   return user;
                 }
-                if (event.person.avatar_url || event.person.role) {
-                  return { ...user, ...event.person };
+                if (person.custom_profile_field) {
+                  return {
+                    ...user,
+                    profile_data: {
+                      ...(user.profile_data: $PropertyType<User, 'profile_data'>),
+                      [person.custom_profile_field.id]: {
+                        value: person.custom_profile_field.value,
+                        rendered_value: person.custom_profile_field.rendered_value,
+                      },
+                    },
+                  };
+                } else if (person.new_email !== undefined) {
+                  return { ...user, email: person.new_email };
                 } else {
-                  return user;
+                  return { ...user, ...person };
                 }
               });
             }