diff --git a/ChangeLog b/ChangeLog
index 441e5f2..c4ff511 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2018-12-06  NIIBE Yutaka  <gniibe@fsij.org>
+
+	* src/usb-ccid.c (ccid_thread): Priority of handling
+	EV_TX_FINISHED is most important.  Don't handle
+	Ack button event when c->tx_busy = 1.
+
 2018-12-05  NIIBE Yutaka  <gniibe@fsij.org>
 
 	* src/openpgp.c (cmd_external_authenticate): Support
@@ -7,10 +13,6 @@
 
 	* src/openpgp-do.c (gpg_data_copy): Fix for NR_DO_UIF_SIG.
 
-2018-11-30  NIIBE Yutaka  <gniibe@fsij.org>
-
-	* src/usb-ccid.c (ccid_thread): Fix another race condition.
-
 2018-11-25  NIIBE Yutaka  <gniibe@fsij.org>
 
 	* VERSION: 1.2.12.
diff --git a/src/usb-ccid.c b/src/usb-ccid.c
index 7056fb9..512ef55 100644
--- a/src/usb-ccid.c
+++ b/src/usb-ccid.c
@@ -1800,7 +1800,7 @@ ccid_thread (void *arg)
 	}
 
 #ifdef ACKBTN_SUPPORT
-      if (c->tx_busy && ack_intr.ready)
+      if (!c->tx_busy && ack_intr.ready)
 	{
 	  ackbtn_disable ();
 	  chopstx_intr_done (&ack_intr);