diff --git a/userapi/internal/api.go b/userapi/internal/api.go
index c1b9bcabf..1b647a0df 100644
--- a/userapi/internal/api.go
+++ b/userapi/internal/api.go
@@ -389,9 +389,9 @@ func (a *UserInternalAPI) queryAppServiceToken(ctx context.Context, token, appSe
 
 	if localpart != "" { // AS is masquerading as another user
 		// Verify that the user is registered
-		account, err := a.AccountDB.GetAccountByLocalpart(ctx, localpart)
-		// Verify that account exists & appServiceID matches
-		if err == nil && account.AppServiceID == appService.ID {
+		_, err := a.AccountDB.GetAccountByLocalpart(ctx, localpart)
+		// Verify that the account belongs to the appservice user namespaces
+		if err == nil && appService.IsInterestedInUserID(appServiceUserID) {
 			// Set the userID of dummy device
 			dev.UserID = appServiceUserID
 			return &dev, nil