diff --git a/docs/plugin-use.md b/docs/plugin-use.md
index a40f18e..b7f6ff1 100644
--- a/docs/plugin-use.md
+++ b/docs/plugin-use.md
@@ -19,7 +19,7 @@
 **Description**: Provides traffic analysis through
   [Piwik](https://www.piwik.org).
 
-**Example**: `(piwik :piwik-url "piwik.example.com")`
+**Example**: `(piwik :piwik-url "piwik.example.com" :piwik-site "example-site")`
 
 ## CL-WHO
 
diff --git a/plugins/piwik.lisp b/plugins/piwik.lisp
index a3e9e5c..75f2eb5 100644
--- a/plugins/piwik.lisp
+++ b/plugins/piwik.lisp
@@ -12,14 +12,14 @@
   _paq.push(['enableLinkTracking']);
 
   (function() {
-    var u="//~a/";
+    var u='//~a/';
     _paq.push(['setTrackerUrl', u+'piwik.php']);
-    _paq.push(['setSiteId', {$IDSITE}]);
+    _paq.push(['setSiteId', '~a']);
     var d=document, g=d.createElement('script'), s=d.getElementsByTagName('script')[0];
     g.type='text/javascript'; g.async=true; g.defer=true; g.src=u+'piwik.js'; s.parentNode.insertBefore(g,s);
   })();
 </script>")
 
-(defun enable (&key piwik-url)
-  (let ((snippet (format nil *piwik-js* piwik-url)))
+(defun enable (&key piwik-url piwik-site)
+  (let ((snippet (format nil *piwik-js* piwik-url piwik-site)))
     (add-injection (constantly snippet) :head)))