diff --git a/keyserver/src/creators/account-creator.js b/keyserver/src/creators/account-creator.js
index ae72d3f66..d23c7c05c 100644
--- a/keyserver/src/creators/account-creator.js
+++ b/keyserver/src/creators/account-creator.js
@@ -1,378 +1,378 @@
 // @flow
 
 import { getRustAPI } from 'rust-node-addon';
 import bcrypt from 'twin-bcrypt';
 
 import bots from 'lib/facts/bots.js';
 import genesis from 'lib/facts/genesis.js';
 import { policyTypes } from 'lib/facts/policies.js';
 import { validUsernameRegex } from 'lib/shared/account-utils.js';
 import type {
   RegisterResponse,
   RegisterRequest,
 } from 'lib/types/account-types.js';
 import type {
   UserDetail,
   ReservedUsernameMessage,
   SignedIdentityKeysBlob,
 } from 'lib/types/crypto-types.js';
 import type {
   PlatformDetails,
   DeviceTokenUpdateRequest,
 } from 'lib/types/device-types.js';
 import type { CalendarQuery } from 'lib/types/entry-types.js';
 import { messageTypes } from 'lib/types/message-types-enum.js';
 import type { SIWESocialProof } from 'lib/types/siwe-types.js';
 import { threadTypes } from 'lib/types/thread-types-enum.js';
 import { ServerError } from 'lib/utils/errors.js';
 import { values } from 'lib/utils/objects.js';
 import { ignorePromiseRejections } from 'lib/utils/promises.js';
 import { reservedUsernamesSet } from 'lib/utils/reserved-users.js';
 import { isValidEthereumAddress } from 'lib/utils/siwe-utils.js';
 
 import createIDs from './id-creator.js';
 import createMessages from './message-creator.js';
 import { createAndPersistOlmSession } from './olm-session-creator.js';
 import {
   createThread,
   createPrivateThread,
   privateThreadDescription,
 } from './thread-creator.js';
 import { dbQuery, SQL } from '../database/database.js';
 import { deleteCookie } from '../deleters/cookie-deleters.js';
 import { fetchThreadInfos } from '../fetchers/thread-fetchers.js';
 import {
   fetchLoggedInUserInfo,
   fetchKnownUserInfos,
 } from '../fetchers/user-fetchers.js';
 import { verifyCalendarQueryThreadIDs } from '../responders/entry-responders.js';
 import { searchForUser } from '../search/users.js';
 import { createNewUserCookie, setNewSession } from '../session/cookies.js';
 import { createScriptViewer } from '../session/scripts.js';
 import type { Viewer } from '../session/viewer.js';
 import { fetchOlmAccount } from '../updaters/olm-account-updater.js';
 import { updateThread } from '../updaters/thread-updaters.js';
 import { viewerAcknowledgmentUpdater } from '../updaters/viewer-acknowledgment-updater.js';
 import { thisKeyserverAdmin } from '../user/identity.js';
 
 const { commbot } = bots;
 
 const ashoatMessages = [
   'welcome to Comm!',
   'as you inevitably discover bugs, have feature requests, or design ' +
     'suggestions, feel free to message them to me in the app.',
 ];
 
 const privateMessages = [privateThreadDescription];
 
 async function createAccount(
   viewer: Viewer,
   request: RegisterRequest,
 ): Promise<RegisterResponse> {
   if (request.password.trim() === '') {
     throw new ServerError('empty_password');
   }
-  if (request.username.search(validUsernameRegex) === -1) {
+  if (
+    request.username.search(validUsernameRegex) === -1 ||
+    isValidEthereumAddress(request.username.toLowerCase())
+  ) {
     throw new ServerError('invalid_username');
   }
 
   const promises = [searchForUser(request.username), thisKeyserverAdmin()];
   const {
     calendarQuery,
     signedIdentityKeysBlob,
     initialNotificationsEncryptedMessage,
   } = request;
   if (calendarQuery) {
     promises.push(verifyCalendarQueryThreadIDs(calendarQuery));
   }
 
   const [existingUser, admin] = await Promise.all(promises);
-  if (
-    reservedUsernamesSet.has(request.username.toLowerCase()) ||
-    isValidEthereumAddress(request.username.toLowerCase())
-  ) {
+  if (reservedUsernamesSet.has(request.username.toLowerCase())) {
     throw new ServerError('username_reserved');
   }
   if (existingUser) {
     throw new ServerError('username_taken');
   }
 
   const hash = bcrypt.hashSync(request.password);
   const time = Date.now();
   const deviceToken = request.deviceTokenUpdateRequest
     ? request.deviceTokenUpdateRequest.deviceToken
     : viewer.deviceToken;
   const [id] = await createIDs('users', 1);
   const newUserRow = [id, request.username, hash, time];
   const newUserQuery = SQL`
     INSERT INTO users(id, username, hash, creation_time)
     VALUES ${[newUserRow]}
   `;
 
   const [userViewerData] = await Promise.all([
     createNewUserCookie(id, {
       platformDetails: request.platformDetails,
       deviceToken,
       signedIdentityKeysBlob,
     }),
     deleteCookie(viewer.cookieID),
     dbQuery(newUserQuery),
   ]);
   viewer.setNewCookie(userViewerData);
 
   if (calendarQuery) {
     await setNewSession(viewer, calendarQuery, 0);
   }
 
   const olmSessionPromise = (async () => {
     if (userViewerData.cookieID && initialNotificationsEncryptedMessage) {
       await createAndPersistOlmSession(
         initialNotificationsEncryptedMessage,
         'notifications',
         userViewerData.cookieID,
       );
     }
   })();
 
   await Promise.all([
     updateThread(
       createScriptViewer(admin.id),
       {
         threadID: genesis().id,
         changes: { newMemberIDs: [id] },
       },
       { forceAddMembers: true, silenceMessages: true, ignorePermissions: true },
     ),
     viewerAcknowledgmentUpdater(viewer, policyTypes.tosAndPrivacyPolicy),
     olmSessionPromise,
   ]);
 
   const [privateThreadResult, ashoatThreadResult] = await Promise.all([
     createPrivateThread(viewer),
     createThread(
       viewer,
       {
         type: threadTypes.PERSONAL,
         initialMemberIDs: [admin.id],
       },
       { forceAddMembers: true },
     ),
   ]);
   const ashoatThreadID = ashoatThreadResult.newThreadID;
   const privateThreadID = privateThreadResult.newThreadID;
 
   let messageTime = Date.now();
   const ashoatMessageDatas = ashoatMessages.map(message => ({
     type: messageTypes.TEXT,
     threadID: ashoatThreadID,
     creatorID: admin.id,
     time: messageTime++,
     text: message,
   }));
   const privateMessageDatas = privateMessages.map(message => ({
     type: messageTypes.TEXT,
     threadID: privateThreadID,
     creatorID: commbot.userID,
     time: messageTime++,
     text: message,
   }));
   const messageDatas = [...ashoatMessageDatas, ...privateMessageDatas];
   const [messageInfos, threadsResult, userInfos, currentUserInfo] =
     await Promise.all([
       createMessages(viewer, messageDatas),
       fetchThreadInfos(viewer),
       fetchKnownUserInfos(viewer),
       fetchLoggedInUserInfo(viewer),
     ]);
   const rawMessageInfos = [
     ...ashoatThreadResult.newMessageInfos,
     ...privateThreadResult.newMessageInfos,
     ...messageInfos,
   ];
 
   ignorePromiseRejections(
     createAndSendReservedUsernameMessage([
       { username: request.username, userID: id },
     ]),
   );
 
   return {
     id,
     rawMessageInfos,
     currentUserInfo,
     cookieChange: {
       threadInfos: threadsResult.threadInfos,
       userInfos: values(userInfos),
     },
   };
 }
 
 export type ProcessSIWEAccountCreationRequest = {
   +address: string,
   +calendarQuery: CalendarQuery,
   +deviceTokenUpdateRequest?: ?DeviceTokenUpdateRequest,
   +platformDetails: PlatformDetails,
   +socialProof: SIWESocialProof,
   +signedIdentityKeysBlob?: ?SignedIdentityKeysBlob,
 };
 // Note: `processSIWEAccountCreation(...)` assumes that the validity of
 //       `ProcessSIWEAccountCreationRequest` was checked at call site.
 async function processSIWEAccountCreation(
   viewer: Viewer,
   request: ProcessSIWEAccountCreationRequest,
 ): Promise<string> {
   const { calendarQuery, signedIdentityKeysBlob } = request;
   await verifyCalendarQueryThreadIDs(calendarQuery);
 
   const time = Date.now();
   const deviceToken = request.deviceTokenUpdateRequest
     ? request.deviceTokenUpdateRequest.deviceToken
     : viewer.deviceToken;
   const [id] = await createIDs('users', 1);
   const newUserRow = [id, request.address, request.address, time];
   const newUserQuery = SQL`
     INSERT INTO users(id, username, ethereum_address, creation_time)
     VALUES ${[newUserRow]}
   `;
   const [userViewerData] = await Promise.all([
     createNewUserCookie(id, {
       platformDetails: request.platformDetails,
       deviceToken,
       socialProof: request.socialProof,
       signedIdentityKeysBlob,
     }),
     deleteCookie(viewer.cookieID),
     dbQuery(newUserQuery),
   ]);
   viewer.setNewCookie(userViewerData);
 
   await setNewSession(viewer, calendarQuery, 0);
 
   await processAccountCreationCommon(viewer);
 
   ignorePromiseRejections(
     createAndSendReservedUsernameMessage([
       { username: request.address, userID: id },
     ]),
   );
 
   return id;
 }
 
 export type ProcessOLMAccountCreationRequest = {
   +userID: string,
   +username: string,
   +walletAddress?: ?string,
   +calendarQuery: CalendarQuery,
   +deviceTokenUpdateRequest?: ?DeviceTokenUpdateRequest,
   +platformDetails: PlatformDetails,
   +signedIdentityKeysBlob: SignedIdentityKeysBlob,
 };
 // Note: `processOLMAccountCreation(...)` assumes that the validity of
 //       `ProcessOLMAccountCreationRequest` was checked at call site.
 async function processOLMAccountCreation(
   viewer: Viewer,
   request: ProcessOLMAccountCreationRequest,
 ): Promise<void> {
   const { calendarQuery, signedIdentityKeysBlob } = request;
   await verifyCalendarQueryThreadIDs(calendarQuery);
 
   const time = Date.now();
   const deviceToken = request.deviceTokenUpdateRequest
     ? request.deviceTokenUpdateRequest.deviceToken
     : viewer.deviceToken;
   const newUserRow = [
     request.userID,
     request.username,
     request.walletAddress,
     time,
   ];
   const newUserQuery = SQL`
     INSERT INTO users(id, username, ethereum_address, creation_time)
     VALUES ${[newUserRow]}
   `;
   const [userViewerData] = await Promise.all([
     createNewUserCookie(request.userID, {
       platformDetails: request.platformDetails,
       deviceToken,
       signedIdentityKeysBlob,
     }),
     deleteCookie(viewer.cookieID),
     dbQuery(newUserQuery),
   ]);
   viewer.setNewCookie(userViewerData);
 
   await setNewSession(viewer, calendarQuery, 0);
 
   await processAccountCreationCommon(viewer);
 }
 
 async function processAccountCreationCommon(viewer: Viewer) {
   const admin = await thisKeyserverAdmin();
 
   await Promise.all([
     updateThread(
       createScriptViewer(admin.id),
       {
         threadID: genesis().id,
         changes: { newMemberIDs: [viewer.userID] },
       },
       { forceAddMembers: true, silenceMessages: true, ignorePermissions: true },
     ),
     viewerAcknowledgmentUpdater(viewer, policyTypes.tosAndPrivacyPolicy),
   ]);
 
   const [privateThreadResult, ashoatThreadResult] = await Promise.all([
     createPrivateThread(viewer),
     createThread(
       viewer,
       {
         type: threadTypes.PERSONAL,
         initialMemberIDs: [admin.id],
       },
       { forceAddMembers: true },
     ),
   ]);
   const ashoatThreadID = ashoatThreadResult.newThreadID;
   const privateThreadID = privateThreadResult.newThreadID;
 
   let messageTime = Date.now();
   const ashoatMessageDatas = ashoatMessages.map(message => ({
     type: messageTypes.TEXT,
     threadID: ashoatThreadID,
     creatorID: admin.id,
     time: messageTime++,
     text: message,
   }));
   const privateMessageDatas = privateMessages.map(message => ({
     type: messageTypes.TEXT,
     threadID: privateThreadID,
     creatorID: commbot.userID,
     time: messageTime++,
     text: message,
   }));
   const messageDatas = [...ashoatMessageDatas, ...privateMessageDatas];
   await Promise.all([createMessages(viewer, messageDatas)]);
 }
 
 async function createAndSendReservedUsernameMessage(
   payload: $ReadOnlyArray<UserDetail>,
 ) {
   const issuedAt = new Date().toISOString();
   const reservedUsernameMessage: ReservedUsernameMessage = {
     statement: 'Add the following usernames to reserved list',
     payload,
     issuedAt,
   };
   const stringifiedMessage = JSON.stringify(reservedUsernameMessage);
 
   const [rustAPI, accountInfo] = await Promise.all([
     getRustAPI(),
     fetchOlmAccount('content'),
   ]);
   const signature = accountInfo.account.sign(stringifiedMessage);
 
   await rustAPI.addReservedUsernames(stringifiedMessage, signature);
 }
 
 export { createAccount, processSIWEAccountCreation, processOLMAccountCreation };
diff --git a/native/account/registration/username-selection.react.js b/native/account/registration/username-selection.react.js
index 864b1291b..b9174db82 100644
--- a/native/account/registration/username-selection.react.js
+++ b/native/account/registration/username-selection.react.js
@@ -1,224 +1,227 @@
 // @flow
 
 import invariant from 'invariant';
 import * as React from 'react';
 import { View, Text } from 'react-native';
 
 import {
   exactSearchUser,
   exactSearchUserActionTypes,
 } from 'lib/actions/user-actions.js';
 import { createLoadingStatusSelector } from 'lib/selectors/loading-selectors.js';
 import { validUsernameRegex } from 'lib/shared/account-utils.js';
 import { useLegacyAshoatKeyserverCall } from 'lib/utils/action-utils.js';
 import { useDispatchActionPromise } from 'lib/utils/redux-promise-utils.js';
+import { isValidEthereumAddress } from 'lib/utils/siwe-utils.js';
 
 import RegistrationButtonContainer from './registration-button-container.react.js';
 import RegistrationButton from './registration-button.react.js';
 import RegistrationContainer from './registration-container.react.js';
 import RegistrationContentContainer from './registration-content-container.react.js';
 import { RegistrationContext } from './registration-context.js';
 import type { RegistrationNavigationProp } from './registration-navigator.react.js';
 import RegistrationTextInput from './registration-text-input.react.js';
 import type { CoolOrNerdMode } from './registration-types.js';
 import {
   type NavigationRoute,
   PasswordSelectionRouteName,
 } from '../../navigation/route-names.js';
 import { useSelector } from '../../redux/redux-utils.js';
 import { useStyles } from '../../themes/colors.js';
 
 const exactSearchUserLoadingStatusSelector = createLoadingStatusSelector(
   exactSearchUserActionTypes,
 );
 
 export type UsernameSelectionParams = {
   +userSelections: {
     +coolOrNerdMode: CoolOrNerdMode,
     +keyserverURL: string,
   },
 };
 
 type UsernameError = 'username_invalid' | 'username_taken';
 
 type Props = {
   +navigation: RegistrationNavigationProp<'UsernameSelection'>,
   +route: NavigationRoute<'UsernameSelection'>,
 };
 function UsernameSelection(props: Props): React.Node {
   const registrationContext = React.useContext(RegistrationContext);
   invariant(registrationContext, 'registrationContext should be set');
   const { cachedSelections, setCachedSelections } = registrationContext;
 
   const [username, setUsername] = React.useState(
     cachedSelections.username ?? '',
   );
-  const validUsername = username.search(validUsernameRegex) > -1;
+  const validUsername =
+    username.search(validUsernameRegex) > -1 &&
+    !isValidEthereumAddress(username.toLowerCase());
 
   const [usernameError, setUsernameError] = React.useState<?UsernameError>();
   const checkUsernameValidity = React.useCallback(() => {
     if (!validUsername) {
       setUsernameError('username_invalid');
       return false;
     }
     setUsernameError(null);
     return true;
   }, [validUsername]);
 
   const { userSelections } = props.route.params;
   const { keyserverURL } = userSelections;
   const serverCallParamOverride = React.useMemo(
     () => ({
       urlPrefix: keyserverURL,
     }),
     [keyserverURL],
   );
 
   const exactSearchUserCall = useLegacyAshoatKeyserverCall(
     exactSearchUser,
     serverCallParamOverride,
   );
   const dispatchActionPromise = useDispatchActionPromise();
   const { navigate } = props.navigation;
   const onProceed = React.useCallback(async () => {
     if (!checkUsernameValidity()) {
       return;
     }
 
     const searchPromise = exactSearchUserCall(username);
     void dispatchActionPromise(exactSearchUserActionTypes, searchPromise);
     const { userInfo } = await searchPromise;
 
     if (userInfo) {
       setUsernameError('username_taken');
       return;
     }
 
     setUsernameError(undefined);
     setCachedSelections(oldUserSelections => ({
       ...oldUserSelections,
       username,
     }));
     navigate<'PasswordSelection'>({
       name: PasswordSelectionRouteName,
       params: {
         userSelections: {
           ...userSelections,
           username,
         },
       },
     });
   }, [
     checkUsernameValidity,
     username,
     exactSearchUserCall,
     dispatchActionPromise,
     setCachedSelections,
     navigate,
     userSelections,
   ]);
 
   const exactSearchUserCallLoading = useSelector(
     state => exactSearchUserLoadingStatusSelector(state) === 'loading',
   );
   let buttonVariant = 'disabled';
   if (exactSearchUserCallLoading) {
     buttonVariant = 'loading';
   } else if (validUsername) {
     buttonVariant = 'enabled';
   }
 
   const styles = useStyles(unboundStyles);
   let errorText;
   if (usernameError === 'username_invalid') {
     errorText = (
       <>
         <Text style={styles.errorText}>Usernames must:</Text>
         <View style={styles.listItem}>
           <Text style={[styles.errorText, styles.listItemNumber]}>{'1. '}</Text>
           <Text style={[styles.errorText, styles.listItemContent]}>
             Be at least one character long.
           </Text>
         </View>
         <View style={styles.listItem}>
           <Text style={[styles.errorText, styles.listItemNumber]}>{'2. '}</Text>
           <Text style={[styles.errorText, styles.listItemContent]}>
             Start with either a letter or a number.
           </Text>
         </View>
         <View style={styles.listItem}>
           <Text style={[styles.errorText, styles.listItemNumber]}>{'3. '}</Text>
           <Text style={[styles.errorText, styles.listItemContent]}>
             Contain only letters, numbers, or the characters “-” and “_”.
           </Text>
         </View>
       </>
     );
   } else if (usernameError === 'username_taken') {
     errorText = (
       <Text style={styles.errorText}>
         Username taken. Please try another one
       </Text>
     );
   }
 
   const shouldAutoFocus = React.useRef(!cachedSelections.username);
   return (
     <RegistrationContainer>
       <RegistrationContentContainer>
         <Text style={styles.header}>Pick a username</Text>
         <RegistrationTextInput
           value={username}
           onChangeText={setUsername}
           placeholder="Username"
           autoFocus={shouldAutoFocus.current}
           autoCorrect={false}
           autoCapitalize="none"
           keyboardType="ascii-capable"
           textContentType="username"
           autoComplete="username-new"
           returnKeyType="go"
           onSubmitEditing={onProceed}
           editable={!exactSearchUserCallLoading}
           onBlur={checkUsernameValidity}
         />
         <View style={styles.error}>{errorText}</View>
       </RegistrationContentContainer>
       <RegistrationButtonContainer>
         <RegistrationButton
           onPress={onProceed}
           label="Next"
           variant={buttonVariant}
         />
       </RegistrationButtonContainer>
     </RegistrationContainer>
   );
 }
 
 const unboundStyles = {
   header: {
     fontSize: 24,
     color: 'panelForegroundLabel',
     paddingBottom: 16,
   },
   error: {
     marginTop: 16,
   },
   errorText: {
     fontFamily: 'Arial',
     fontSize: 15,
     lineHeight: 20,
     color: 'redText',
   },
   listItem: {
     flexDirection: 'row',
   },
   listItemNumber: {
     fontWeight: 'bold',
   },
   listItemContent: {
     flexShrink: 1,
   },
 };
 
 export default UsernameSelection;