diff --git a/PreferencesPlugin/lib/Foswiki/Plugins/PreferencesPlugin.pm b/PreferencesPlugin/lib/Foswiki/Plugins/PreferencesPlugin.pm
index ca3ef68042..a3f0439043 100644
--- a/PreferencesPlugin/lib/Foswiki/Plugins/PreferencesPlugin.pm
+++ b/PreferencesPlugin/lib/Foswiki/Plugins/PreferencesPlugin.pm
@@ -79,7 +79,7 @@ sub beforeCommonTagsHandler {
 
     my $query = Foswiki::Func::getCgiQuery();
 
-    my $action = lc( $query->param('prefsaction') );
+    my $action = lc( $query->param('prefsaction') || '' );
     $query->Delete('prefsaction');
     $action =~ s/\s.*$//;