diff --git a/plugins/adduser b/plugins/adduser
index 52234de..24b764d 100644
--- a/plugins/adduser
+++ b/plugins/adduser
@@ -1,5 +1,7 @@
 #!perl
 
+use List::Util qw(any);
+
 HELP1 "adduser <name>" => "Create an account";
 
 sub command :Tab(adduser) ($self, $cart, $command, @) {
@@ -25,6 +27,13 @@ sub username($self, $cart, $name, @) {
     return REJECT, "That name already exists."
         if defined parse_user($name);
 
+    for my $plugin (RevBank::Plugins->new) {
+        my $id = $plugin->id;
+
+        return REJECT, "That name would clash with the '$id' plugin."
+            if any sub { $_ eq $name }, $plugin->Tab('command');
+    }
+
     RevBank::Users::create( $name );
 
     return ACCEPT;