diff --git a/plinth/modules/repro/__init__.py b/plinth/modules/repro/__init__.py
index 77e67b379..1d1443e2d 100644
--- a/plinth/modules/repro/__init__.py
+++ b/plinth/modules/repro/__init__.py
@@ -28,7 +28,6 @@ from plinth import cfg
 from plinth import frontpage
 from plinth import service as service_module
 from plinth.views import ServiceView
-
 version = 2
 
 depends = ['apps']
@@ -62,6 +61,7 @@ description = [
 
 service = None
 
+reserved_usernames = ['repro']
 
 def init():
     """Initialize the repro module."""
diff --git a/plinth/modules/users/forms.py b/plinth/modules/users/forms.py
index 4b0bf5b9b..6c6f1961c 100644
--- a/plinth/modules/users/forms.py
+++ b/plinth/modules/users/forms.py
@@ -30,23 +30,7 @@ from plinth.errors import ActionError
 from plinth.modules import first_boot
 from plinth.modules.security import set_restricted_access
 from plinth.utils import is_user_admin
-
-# Usernames used by optional services (that might not be installed yet).
-RESERVED_USERNAMES = [
-    'debian-deluged',
-    'Debian-minetest',
-    'debian-tor',
-    'debian-transmission',
-    'ejabberd',
-    'ez-ipupd',
-    'monkeysphere',
-    'mumble-server',
-    'node-restore',
-    'quasselcore',
-    'radicale',
-    'repro',
-    'privoxy',
-]
+from plinth import module_loader
 
 GROUP_CHOICES = (
     ('admin', _('admin')),
@@ -78,8 +62,10 @@ class ValidNewUsernameCheckMixin(object):
         except subprocess.CalledProcessError:
             pass
 
-        if username in RESERVED_USERNAMES:
-            return False
+        for module_name, module in module_loader.loaded_modules.items():
+            for reserved_username in getattr(module, 'reserved_usernames', []):
+                if username == reserved_username:
+                    return False
 
         return True