diff --git a/ChangeLog b/ChangeLog
index 8d4941b..73739ed 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+2013-10-08  Niibe Yutaka  <gniibe@fsij.org>
+
+	* src/openpgp.c (modify_binary): Allow odd size of certificate.
+
 2013-10-07  Niibe Yutaka  <gniibe@fsij.org>
 
 	* polarssl/library/bignum.c (mpi_sub_hlp): Return CARRY.
diff --git a/src/openpgp.c b/src/openpgp.c
index 2007a2e..f745a53 100644
--- a/src/openpgp.c
+++ b/src/openpgp.c
@@ -995,6 +995,10 @@ modify_binary (uint8_t op, uint8_t p1, uint8_t p2, int len)
   DEBUG_SHORT (len);
   DEBUG_SHORT (offset);
 
+  if (file_id == FILEID_CH_CERTIFICATE && (len&1))
+    /* It's OK the size of last write is odd.  */
+    apdu.cmd_apdu_data[len++] = 0xff;
+
   r = flash_write_binary (file_id, apdu.cmd_apdu_data, len, offset);
   if (r < 0)
     {