diff --git a/openid-key.asd b/openid-key.asd
index 28d977f..a5a1a3b 100644
--- a/openid-key.asd
+++ b/openid-key.asd
@@ -3,14 +3,14 @@
 |#
 
 (defsystem "openid-key"
-  :version "0.1.0"
+  :version "0.1.1"
   :author "Koga Kazuo"
   :license "MIT"
-  :depends-on ("dexador"
+  :depends-on ("cl-base64"
+               "dexador"
                "ironclad"
                "jonathan"
                "local-time"
-               "qbase64"
                "quri"
                "trivial-rfc-1123")
   :components ((:module "src"
diff --git a/src/openid-key.lisp b/src/openid-key.lisp
index 362f7e1..553ec64 100644
--- a/src/openid-key.lisp
+++ b/src/openid-key.lisp
@@ -33,18 +33,9 @@
         (setf (quri:uri-path config) well-known))
     config))
 
-(defun padding (s)
-  (let ((p (- 4 (rem (length s) 4))))
-    (case p
-      ((1) (concatenate 'string s "="))
-      ((2) (concatenate 'string s "=="))
-      ((3) (concatenate 'string s "==="))
-      (otherwise s))))
-
 (defun b64-integer (s)
-  (let* ((b (qbase64:decode-string (padding s) :scheme :uri))
-         (v (make-array (length b) :element-type '(unsigned-byte 8) :initial-contents b)))
-    (ironclad:octets-to-integer v)))
+  (ironclad:octets-to-integer
+   (base64:base64-string-to-usb8-array s :uri t)))
 
 (defun jwk-key (jwk)
   (when (equal "RSA" (cdr (assoc "kty" jwk :test 'equal)))