diff --git a/storage/storage.lisp b/storage/storage.lisp
index 2f06e30..3d1cf9a 100644
--- a/storage/storage.lisp
+++ b/storage/storage.lisp
@@ -30,13 +30,16 @@
    (params :initarg :params)
    (config :reader config :initarg :config)))
 
+(defclass db-engine-pg (db-engine) ())
+
 (defun make-engine () 
   (let ((backend (getf *db-config* :backend)))
     (funcall (getf *backends* backend) *db-config*)))
 
-(defgeneric timestamp-to-sql (engine ts))
-
-(defmethod timestamp-to-sql ((engine db-engine) ts) ts)
+(defgeneric timestamp-to-sql (engine ts)
+  (:method ((engine db-engine) ts) ts)
+  (:method ((engine db-engine-pg) ts)
+    (format nil "~a" (local-time:universal-to-timestamp ts))))
 
 (defclass storage ()
   ((engine :reader engine :initarg :engine)
@@ -98,7 +101,3 @@
                    :connect #'(lambda () 
                                 (apply #'dbi:connect-cached db-type conn-args)))))
 
-(defclass db-engine-pg (db-engine) ())
-
-(defmethod timestamp-to-sql ((engine db-engine-pg) ts)
-  (format nil "~a" (local-time:universal-to-timestamp ts)))