diff --git a/plinth/modules/deluge/__init__.py b/plinth/modules/deluge/__init__.py
index f60309c29..1b78b7435 100644
--- a/plinth/modules/deluge/__init__.py
+++ b/plinth/modules/deluge/__init__.py
@@ -49,6 +49,7 @@ description = [
       'it immediately after enabling this service.')
 ]
 
+reserved_usernames = ['debian-deluged']
 
 def init():
     """Initialize the Deluge module."""
diff --git a/plinth/modules/dynamicdns/__init__.py b/plinth/modules/dynamicdns/__init__.py
index 0579e4b18..2108352fa 100644
--- a/plinth/modules/dynamicdns/__init__.py
+++ b/plinth/modules/dynamicdns/__init__.py
@@ -50,6 +50,7 @@ description = [
       'name, they will get a response with your current IP address.')
 ]
 
+reserved_usernames = ['ez-ipupd']
 
 def init():
     """Initialize the module."""
diff --git a/plinth/modules/ejabberd/__init__.py b/plinth/modules/ejabberd/__init__.py
index b2c1ffe02..9c75812b4 100644
--- a/plinth/modules/ejabberd/__init__.py
+++ b/plinth/modules/ejabberd/__init__.py
@@ -52,6 +52,8 @@ description = [
       '>XMPP client</a>.'),
 ]
 
+reserved_usernames = ['ejabberd']
+
 service = None
 
 logger = logging.getLogger(__name__)
diff --git a/plinth/modules/minetest/__init__.py b/plinth/modules/minetest/__init__.py
index 66dfc8682..9f2b6cd7f 100644
--- a/plinth/modules/minetest/__init__.py
+++ b/plinth/modules/minetest/__init__.py
@@ -57,6 +57,8 @@ description = [
           'is needed.'), box_name=_(cfg.box_name)),
 ]
 
+reserved_usernames = ['Debian-minetest']
+
 CONFIG_FILE = '/etc/minetest/minetest.conf'
 AUG_PATH = '/files' + CONFIG_FILE + '/.anon'
 
diff --git a/plinth/modules/monkeysphere/__init__.py b/plinth/modules/monkeysphere/__init__.py
index e48ee24cd..b0046eda7 100644
--- a/plinth/modules/monkeysphere/__init__.py
+++ b/plinth/modules/monkeysphere/__init__.py
@@ -51,6 +51,8 @@ description = [
       'website</a>.')
 ]
 
+reserved_usernames = ['monkeysphere']
+
 
 def init():
     """Initialize the monkeysphere module."""
diff --git a/plinth/modules/mumble/__init__.py b/plinth/modules/mumble/__init__.py
index 2e4c8064b..c368e984d 100644
--- a/plinth/modules/mumble/__init__.py
+++ b/plinth/modules/mumble/__init__.py
@@ -51,6 +51,8 @@ description = [
       'from your desktop and Android devices are available.')
 ]
 
+reserved_usernames = ['mumble-server']
+
 
 def init():
     """Intialize the Mumble module."""
diff --git a/plinth/modules/privoxy/__init__.py b/plinth/modules/privoxy/__init__.py
index 98bbad0b7..aea63e38a 100644
--- a/plinth/modules/privoxy/__init__.py
+++ b/plinth/modules/privoxy/__init__.py
@@ -59,6 +59,8 @@ description = [
         box_name=_(cfg.box_name)),
 ]
 
+reserved_usernames = ['privoxy']
+
 service = None
 
 
diff --git a/plinth/modules/quassel/__init__.py b/plinth/modules/quassel/__init__.py
index 519912422..1c1d82dbe 100644
--- a/plinth/modules/quassel/__init__.py
+++ b/plinth/modules/quassel/__init__.py
@@ -59,6 +59,8 @@ description = [
       'are available.'),
 ]
 
+reserved_usernames = ['quasselcore']
+
 
 def init():
     """Initialize the quassel module."""
diff --git a/plinth/modules/radicale/__init__.py b/plinth/modules/radicale/__init__.py
index 4a4fcfb6f..1e0beccd7 100644
--- a/plinth/modules/radicale/__init__.py
+++ b/plinth/modules/radicale/__init__.py
@@ -52,6 +52,8 @@ description = [
           'login.'), box_name=_(cfg.box_name)),
 ]
 
+reserved_usernames = ['radicale']
+
 CONFIG_FILE = '/etc/radicale/config'
 
 
diff --git a/plinth/modules/repro/__init__.py b/plinth/modules/repro/__init__.py
index 1d1443e2d..8ec5fb546 100644
--- a/plinth/modules/repro/__init__.py
+++ b/plinth/modules/repro/__init__.py
@@ -59,9 +59,10 @@ description = [
       'service and re-enable it.'),
 ]
 
+reserved_usernames = ['repro']
+
 service = None
 
-reserved_usernames = ['repro']
 
 def init():
     """Initialize the repro module."""
diff --git a/plinth/modules/restore/__init__.py b/plinth/modules/restore/__init__.py
index 14030c60b..5747a6ad0 100644
--- a/plinth/modules/restore/__init__.py
+++ b/plinth/modules/restore/__init__.py
@@ -49,6 +49,8 @@ description = [
       '<a href=\'/restore/\'>reStore web-interface</a>.')
 ]
 
+reserved_usernames = ['node-restores']
+
 service = None
 
 
diff --git a/plinth/modules/tor/__init__.py b/plinth/modules/tor/__init__.py
index 498c21aeb..f009948dc 100644
--- a/plinth/modules/tor/__init__.py
+++ b/plinth/modules/tor/__init__.py
@@ -50,6 +50,8 @@ description = [
       'Tor Browser</a>.')
 ]
 
+reserved_usernames = ['debian-tor']
+
 socks_service = None
 bridge_service = None
 
diff --git a/plinth/modules/transmission/__init__.py b/plinth/modules/transmission/__init__.py
index 84455603b..0d9ec85c9 100644
--- a/plinth/modules/transmission/__init__.py
+++ b/plinth/modules/transmission/__init__.py
@@ -46,6 +46,8 @@ description = [
     _('Access the web interface at <a href="/transmission">/transmission</a>.')
 ]
 
+reserved_usernames = ['debian-transmission']
+
 service = None