diff --git a/qse/include/qse/si/spl.h b/qse/include/qse/si/spl.h
index 33bfa9a9..fcd351cd 100644
--- a/qse/include/qse/si/spl.h
+++ b/qse/include/qse/si/spl.h
@@ -210,20 +210,20 @@ asm void qse_spl_unlock (qse_spl_t* spl)
 		unsigned int rc;
 
 		__asm__ volatile (
-			"__back:\n"
+			"1:\n"
 			"lwarx        %0,0,%1\n"  /* load and reserve. rc(%0) = *spl(%1) */
 			"cmpwi        cr0,%0,0\n" /* cr0 = (rc compare-with 0) */
 			"li           %0,0\n"     /* rc = 0(failure) */
-			"bne          cr0,__exit\n"   /* if cr0 != 0, goto _exit; */
+			"bne          cr0,2f\n"   /* if cr0 != 0, goto 2; */
 			"li           %0,1\n"     /* rc = 1(success) */
 			"stwcx.       %0,0,%1\n"  /* *spl(%1) = 1(value in rc) if reserved */
-			"bne          cr0,__back\n"   /* if reservation is lost, goto __back */
+			"bne          cr0,1b\n"   /* if reservation is lost, goto 1 */
 		#if 1
 			"lwsync\n"
 		#else
 			"isync\n"
 		#endif
-			"__exit:\n"
+			"2:\n"
 			: "=&r"(rc)
 			: "r"(spl)
 			: "cr0", "memory"
diff --git a/qse/samples/si/spl01.c b/qse/samples/si/spl01.c
index 814fd74f..11e5b5dd 100644
--- a/qse/samples/si/spl01.c
+++ b/qse/samples/si/spl01.c
@@ -10,6 +10,7 @@
 
 #include <signal.h>
 #include <string.h>
+#include <sched.h>
 
 static int g_stopreq = 0;
 static qse_ntime_t sleep_interval = { 1, 0 };
@@ -33,6 +34,7 @@ static int thr_func (qse_thr_t* thr, void* ctx)
 		qse_printf (QSE_T("%s: [% 16d] [% 16d] [% 16d]\n"), xtn->name, i, i, i);
 		qse_spl_unlock (xtn->spl);
 		i++;
+		if (!(i % 15)) sched_yield();
 		/*qse_sleep (&sleep_interval);*/
 	}