diff --git a/travo/course.py b/travo/course.py
index c422a94daf03573b9bb987533bf99c7b05aefc6c..298daad50dd0c3b79637d004a29431ecaecd627e 100644
--- a/travo/course.py
+++ b/travo/course.py
@@ -2,6 +2,7 @@ import logging
 import os.path
 from dataclasses import dataclass, field
 from deprecation import deprecated  # type: ignore
+import re
 import subprocess
 from typing import List, Optional, Tuple, Union
 
@@ -17,6 +18,19 @@ def missing_course() -> 'Course':
     raise ValueError("missing required argument: 'course'")
 
 
+"""
+Characters that are forbidden in GitLab group names
+
+https://docs.gitlab.com/ee/user/reserved_names.html#limitations-on-project-and-group-names
+
+Test:
+
+    >>> re.sub(forbidden_in_gitlab_group_name, " ", "a-s+d o_98#(*&$'sadf.)")
+    '-a+sd o_98 (    sadf.)'
+"""
+forbidden_in_gitlab_group_name = re.compile(r"[^.()\w+-]")
+
+
 @dataclass
 class CourseAssignment(Assignment):
     # Until Python 3.10 and keyword only fields, a subdataclass
@@ -124,6 +138,10 @@ class CourseAssignment(Assignment):
         assert not isinstance(user, AnonymousUser)
         assert user.name is not None
         name = user.name
+
+        # Replace forbidden characters by spaces
+        name = re.sub(forbidden_in_gitlab_group_name, " ", name)
+
         if self.course.group_submissions:
             name = _('submission group name', name=user.name)
         components = [name, self.course.name]