diff --git a/ChangeLog b/ChangeLog
index f5cb0d5..1c879e8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
 2016-05-18  Niibe Yutaka  <gniibe@fsij.org>
 
+	* src/gnuk.ld.in: Tweak thread size.
+	* src/main.c (main): Use chopstx_setpriority.
+	* src/usb-icc.c (ccid_init): Use new eventflag API.
+
 	* regnual/regnual.c (nvic_enable_intr): New.
 	(main): Call nvic_enable_intr.
 
diff --git a/chopstx b/chopstx
index cea3200..5e33e7f 160000
--- a/chopstx
+++ b/chopstx
@@ -1 +1 @@
-Subproject commit cea3200e4846276b2406c3e5059bf756ca0013b7
+Subproject commit 5e33e7f468eda8466da1dd55cacc88ee4915d18f
diff --git a/src/gnuk.ld.in b/src/gnuk.ld.in
index 1acfc66..3a5c870 100644
--- a/src/gnuk.ld.in
+++ b/src/gnuk.ld.in
@@ -2,11 +2,11 @@
  * ST32F103 memory setup.
  */
 __main_stack_size__      = 0x0080;      /* Exception handlers     */
-__process0_stack_size__  = 0x0100;      /* main */
-__process1_stack_size__  = 0x0120;      /* ccid */
-__process2_stack_size__  = 0x01a0;      /* rng */
+__process0_stack_size__  = 0x0180;      /* main */
+__process1_stack_size__  = 0x0160;      /* ccid */
+__process2_stack_size__  = 0x0140;      /* rng */
 __process3_stack_size__  = 0x1640;      /* gpg */
-__process4_stack_size__  = 0x0120;      /* intr: usb */
+__process4_stack_size__  = 0x0100;      /* intr: usb */
 __process5_stack_size__  = @MSC_SIZE@;  /* msc */
 __process6_stack_size__  = @TIM_SIZE@;  /* intr: timer */
 __process7_stack_size__  = @EXT_SIZE@;  /* intr: ext */
diff --git a/src/main.c b/src/main.c
index 5d5fb2b..ea6bf53 100644
--- a/src/main.c
+++ b/src/main.c
@@ -94,7 +94,7 @@ _write (const char *s, int size)
 }
 #endif
 
-extern void *USBthread (void *arg);
+extern void *ccid_thread (void *arg);
 
 
 /*
@@ -304,7 +304,7 @@ main (int argc, char *argv[])
 
   adc_init ();
 
-  eventflag_init (&led_event, chopstx_main);
+  eventflag_init (&led_event);
 
   random_init ();
 
@@ -313,7 +313,7 @@ main (int argc, char *argv[])
 #endif
 
   ccid_thd = chopstx_create (PRIO_CCID, __stackaddr_ccid, __stacksize_ccid,
-			     USBthread, NULL);
+			     ccid_thread, NULL);
 
 #ifdef PINPAD_CIR_SUPPORT
   cir_init ();
@@ -325,7 +325,7 @@ main (int argc, char *argv[])
   usb_thd = chopstx_create (PRIO_USB, __stackaddr_usb, __stacksize_usb,
 			    usb_intr, NULL);
 
-  chopstx_main_init (PRIO_MAIN);
+  chopstx_setpriority (PRIO_MAIN);
 
   while (1)
     {
diff --git a/src/usb-icc.c b/src/usb-icc.c
index 9460620..7935dee 100644
--- a/src/usb-icc.c
+++ b/src/usb-icc.c
@@ -1,7 +1,7 @@
 /*
  * usb-icc.c -- USB CCID protocol handling
  *
- * Copyright (C) 2010, 2011, 2012, 2013, 2014, 2015
+ * Copyright (C) 2010, 2011, 2012, 2013, 2014, 2015, 2016
  *               Free Software Initiative of Japan
  * Author: NIIBE Yutaka <gniibe@fsij.org>
  *
@@ -248,7 +248,7 @@ static void ccid_reset (struct ccid *c)
 }
 
 static void ccid_init (struct ccid *c, struct ep_in *epi, struct ep_out *epo,
-		       struct apdu *a, chopstx_t thd)
+		       struct apdu *a)
 {
   icc_state_p = &c->icc_state;
 
@@ -260,9 +260,9 @@ static void ccid_init (struct ccid *c, struct ep_in *epi, struct ep_out *epo,
   memset (&c->icc_header, 0, sizeof (struct icc_header));
   c->sw1sw2[0] = 0x90;
   c->sw1sw2[1] = 0x00;
-  eventflag_init (&c->ccid_comm, thd);
+  eventflag_init (&c->ccid_comm);
   c->application = 0;
-  eventflag_init (&c->openpgp_comm, 0);
+  eventflag_init (&c->openpgp_comm);
   c->epi = epi;
   c->epo = epo;
   c->a = a;
@@ -1329,33 +1329,23 @@ ccid_usb_reset (void)
 
 #define GPG_THREAD_TERMINATED 0xffff
 
-static void *ccid_thread (chopstx_t) __attribute__ ((noinline));
-
-void * __attribute__ ((naked))
-USBthread (void *arg)
-{
-  chopstx_t thd;
-  (void)arg;
-
-  asm ("mov	%0, sp" : "=r" (thd));
-  return ccid_thread (thd);
-}
-
 #define NOTIFY_SLOT_CHANGE 0x50
 
-static void * __attribute__ ((noinline))
-ccid_thread (chopstx_t thd)
+void *
+ccid_thread (void *arg)
 {
   struct ep_in *epi = &endpoint_in;
   struct ep_out *epo = &endpoint_out;
   struct ccid *c = &ccid;
   struct apdu *a = &apdu;
 
+  (void)arg;
+
  reset:
   epi_init (epi, ENDP1, notify_tx, c);
   epo_init (epo, ENDP1, notify_icc, c);
   apdu_init (a);
-  ccid_init (c, epi, epo, a, thd);
+  ccid_init (c, epi, epo, a);
 
   icc_prepare_receive (c);
   while (1)