diff --git a/application/controllers/ShowController.php b/application/controllers/ShowController.php
index f029b81..427142e 100644
--- a/application/controllers/ShowController.php
+++ b/application/controllers/ShowController.php
@@ -133,7 +133,7 @@ class ShowController extends Controller
             );
 
         foreach ($this->params->toArray() as $val) {
-            $query->where($val[0], $val[1]);
+            $query->where($val[0], urldecode($val[1]));
         }
 
         $img = $this->applyGraphParams(current($query->getImages($template)))
diff --git a/library/Graphite/GraphiteUtil.php b/library/Graphite/GraphiteUtil.php
index efafec6..2c3fe6e 100644
--- a/library/Graphite/GraphiteUtil.php
+++ b/library/Graphite/GraphiteUtil.php
@@ -106,6 +106,6 @@ class GraphiteUtil
 
     public static function escape($string)
     {
-        return preg_replace('/[^a-zA-Z0-9\*\-]/', '_', $string);
+        return preg_replace('/[^a-zA-Z0-9\*\-:]/', '_', $string);
     }
 }