diff --git a/ChangeLog b/ChangeLog
index 081ceb5..41b41ac 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2013-02-22  Niibe Yutaka  <gniibe@fsij.org>
+
+	* src/openpgp.c (ECDSA_SIGNATURE_LENGTH): It's 65.
+
+	* src/call-ec_p256.c (ecdsa_sign): Add a header byte.
+
 2013-02-21  Niibe Yutaka  <gniibe@fsij.org>
 
 	* src/gnuk.ld.in (MEMORY): Fix adding FLASH_SIZE unit.
diff --git a/src/call-ec_p256.c b/src/call-ec_p256.c
index a929fb1..23f4225 100644
--- a/src/call-ec_p256.c
+++ b/src/call-ec_p256.c
@@ -43,6 +43,8 @@ ecdsa_sign (const uint8_t *hash, uint8_t *output,
   bn256 r[1], s[1], z[1], d[1];
   uint8_t *p;
 
+  *output++ = '\x04';		/* No compression.  */
+
   p = (uint8_t *)d;
   for (i = 0; i < ECDSA_BYTE_SIZE; i++)
     p[ECDSA_BYTE_SIZE - i - 1] = kd->data[i];
diff --git a/src/openpgp.c b/src/openpgp.c
index 5275d15..4f72281 100644
--- a/src/openpgp.c
+++ b/src/openpgp.c
@@ -879,7 +879,7 @@ cmd_internal_authenticate (void)
 }
 #else
 #define ECDSA_P256_HASH_LEN 32
-#define ECDSA_SIGNATURE_LENGTH 64
+#define ECDSA_SIGNATURE_LENGTH (1+64)
 
 static void
 cmd_internal_authenticate (void)