diff --git a/src/controllers/GroupsController.ts b/src/controllers/GroupsController.ts
index 356e0de..e0e4425 100644
--- a/src/controllers/GroupsController.ts
+++ b/src/controllers/GroupsController.ts
@@ -532,11 +532,8 @@ export class GroupsController {
 	 */
 	public static async RemoveMembership(h: RequestHandler) {
 		const groupID = await h.postGroupIDWithAccess("id", GroupsAccessLevel.LIMITED_ACCESS);
-		const level = await GroupsHelper.GetMembershipLevel(groupID, h.getUserId());
 
-		// TODO : use new method
-		if(level == GroupMembershipLevels.ADMINISTRATOR
-			&& await GroupsHelper.CountMembersAtLevel(groupID, GroupMembershipLevels.ADMINISTRATOR) == 1)
+		if(await GroupsHelper.IsLastAdmin(groupID, h.getUserId()))
 			h.error(401, "You are the last administrator of the group!");
 		
 		// Delete mebmership
diff --git a/src/helpers/GroupsHelper.ts b/src/helpers/GroupsHelper.ts
index ee6a8d4..d78ad2b 100644
--- a/src/helpers/GroupsHelper.ts
+++ b/src/helpers/GroupsHelper.ts
@@ -398,7 +398,7 @@ export class GroupsHelper {
 	 * @param groupID Target group ID
 	 * @param userID Target user ID
 	 */
-	private static async IsLastAdmin(groupID: number, userID: number) : Promise<boolean> {
+	public static async IsLastAdmin(groupID: number, userID: number) : Promise<boolean> {
 		return await this.GetMembershipLevel(groupID, userID) == GroupMembershipLevels.ADMINISTRATOR
 			&& await GroupsHelper.CountMembersAtLevel(groupID, GroupMembershipLevels.ADMINISTRATOR) == 1;
 	}