diff --git a/api4/oauth_test.go b/api4/oauth_test.go
index 8cf20ca5e3..6bbd99ccca 100644
--- a/api4/oauth_test.go
+++ b/api4/oauth_test.go
@@ -1127,15 +1127,8 @@ func closeBody(r *http.Response) {
 type MattermostTestProvider struct {
 }
 
-func (m *MattermostTestProvider) GetIdentifier() string {
-	return model.SERVICE_GITLAB
-}
-
 func (m *MattermostTestProvider) GetUserFromJson(data io.Reader) *model.User {
-	return model.UserFromJson(data)
-}
-
-func (m *MattermostTestProvider) GetAuthDataFromJson(data io.Reader) string {
-	authData := model.UserFromJson(data)
-	return authData.Email
+	user := model.UserFromJson(data)
+	user.AuthData = &user.Email
+	return user
 }
diff --git a/app/oauth.go b/app/oauth.go
index 477c0aeaf4..80fe4342e6 100644
--- a/app/oauth.go
+++ b/app/oauth.go
@@ -457,7 +457,13 @@ func (a *App) LoginByOAuth(service string, userData io.Reader, teamId string) (*
 		return nil, model.NewAppError("LoginByOAuth", "api.user.login_by_oauth.not_available.app_error",
 			map[string]interface{}{"Service": strings.Title(service)}, "", http.StatusNotImplemented)
 	} else {
-		authData = provider.GetAuthDataFromJson(bytes.NewReader(buf.Bytes()))
+		authUser := provider.GetUserFromJson(bytes.NewReader(buf.Bytes()))
+
+		if authUser.AuthData != nil {
+			authData = *authUser.AuthData
+		} else {
+			authData = ""
+		}
 	}
 
 	if len(authData) == 0 {
diff --git a/einterfaces/oauthproviders.go b/einterfaces/oauthproviders.go
index ed54a204a0..178c17c116 100644
--- a/einterfaces/oauthproviders.go
+++ b/einterfaces/oauthproviders.go
@@ -10,9 +10,7 @@ import (
 )
 
 type OauthProvider interface {
-	GetIdentifier() string
 	GetUserFromJson(data io.Reader) *model.User
-	GetAuthDataFromJson(data io.Reader) string
 }
 
 var oauthProviders = make(map[string]OauthProvider)
diff --git a/model/gitlab/gitlab.go b/model/gitlab/gitlab.go
index 7e0cb10af1..f0a388b6a9 100644
--- a/model/gitlab/gitlab.go
+++ b/model/gitlab/gitlab.go
@@ -47,7 +47,7 @@ func userFromGitLabUser(glu *GitLabUser) *model.User {
 		user.FirstName = glu.Name
 	}
 	user.Email = glu.Email
-	userId := strconv.FormatInt(glu.Id, 10)
+	userId := glu.getAuthData()
 	user.AuthData = &userId
 	user.AuthService = model.USER_AUTH_SERVICE_GITLAB
 
@@ -90,10 +90,6 @@ func (glu *GitLabUser) getAuthData() string {
 	return strconv.FormatInt(glu.Id, 10)
 }
 
-func (m *GitLabProvider) GetIdentifier() string {
-	return model.USER_AUTH_SERVICE_GITLAB
-}
-
 func (m *GitLabProvider) GetUserFromJson(data io.Reader) *model.User {
 	glu := gitLabUserFromJson(data)
 	if glu.IsValid() {
@@ -102,13 +98,3 @@ func (m *GitLabProvider) GetUserFromJson(data io.Reader) *model.User {
 
 	return &model.User{}
 }
-
-func (m *GitLabProvider) GetAuthDataFromJson(data io.Reader) string {
-	glu := gitLabUserFromJson(data)
-
-	if glu.IsValid() {
-		return glu.getAuthData()
-	}
-
-	return ""
-}