diff --git a/src/VoipUserMapper.ts b/src/VoipUserMapper.ts
index c5de686ab8..a4f5822065 100644
--- a/src/VoipUserMapper.ts
+++ b/src/VoipUserMapper.ts
@@ -26,13 +26,15 @@ export function voipUserMapperEnabled(): boolean {
     return SdkConfig.get()['voip_mxid_translate_pattern'] !== undefined;
 }
 
-function userToVirtualUser(userId: string, templateString?: string): string {
+// only exported for tests
+export function userToVirtualUser(userId: string, templateString?: string): string {
     if (templateString === undefined) templateString = SdkConfig.get()['voip_mxid_translate_pattern'];
     if (!templateString) return null;
     return templateString.replace('${mxid}', encodeURIComponent(userId).replace(/%/g, '=').toLowerCase());
 }
 
-function virtualUserToUser(userId: string, templateString?: string): string {
+// only exported for tests
+export function virtualUserToUser(userId: string, templateString?: string): string {
     if (templateString === undefined) templateString = SdkConfig.get()['voip_mxid_translate_pattern'];
     if (!templateString) return null;
 
diff --git a/test/VoipUserMapper-test.ts b/test/VoipUserMapper-test.ts
index a736efd6be..ee45379e4c 100644
--- a/test/VoipUserMapper-test.ts
+++ b/test/VoipUserMapper-test.ts
@@ -18,7 +18,7 @@ import { userToVirtualUser, virtualUserToUser } from '../src/VoipUserMapper';
 
 const templateString = '@_greatappservice_${mxid}:frooble.example';
 const realUser = '@alice:boop.example';
-const virtualUser = "@_greatappservice_%40alice%3Aboop.example:frooble.example";
+const virtualUser = "@_greatappservice_=40alice=3aboop.example:frooble.example";
 
 describe('VoipUserMapper', function() {
     it('translates users to virtual users', function() {