diff --git a/lib/RevBank/Users.pm b/lib/RevBank/Users.pm
index b0d0d09..14469ee 100644
--- a/lib/RevBank/Users.pm
+++ b/lib/RevBank/Users.pm
@@ -98,13 +98,18 @@ sub is_special($username) {
     return $username =~ /^[-+*]/;
 }
 
-sub parse_user($username) {
+sub parse_user($username, $allow_invalid = 0) {
     return undef if is_hidden($username);
 
     my $users = _read();
-    return exists $users->{ lc $username }
-        ? $users->{ lc $username }->[0]
-        : undef;
+
+    exists $users->{ lc $username }
+        or return undef;
+
+    $allow_invalid or defined balance($username)
+        or return undef;
+
+    return $users->{ lc $username }->[0];
 }
 
 sub assert_user($username) {
diff --git a/plugins/adduser b/plugins/adduser
index b99d2b3..5da25f2 100644
--- a/plugins/adduser
+++ b/plugins/adduser
@@ -27,6 +27,9 @@ sub username($self, $cart, $name, @) {
     return REJECT, "That name already exists."
         if defined parse_user($name);
 
+    return REJECT, "That name is not available."
+        if defined parse_user($name, 1);
+
     for my $plugin (RevBank::Plugins->new) {
         my $id = $plugin->id;