diff --git a/qse/include/qse/si/spl.h b/qse/include/qse/si/spl.h
index c826e9da..33bfa9a9 100644
--- a/qse/include/qse/si/spl.h
+++ b/qse/include/qse/si/spl.h
@@ -211,13 +211,13 @@ asm void qse_spl_unlock (qse_spl_t* spl)
 
 		__asm__ volatile (
 			"__back:\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-            __exit\n"   /* if cr0 != 0, goto _exit; */
-			"li              %0,1\n"     /* rc = 1(success) */
-			"stwcx.          %0,0,%1\n"  /* *spl(%1) = 1(value in rc) if reserved */
-			"bne-            __back\n"   /* if reservation is lost, goto __back */
+			"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; */
+			"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 */
 		#if 1
 			"lwsync\n"
 		#else
@@ -233,20 +233,17 @@ asm void qse_spl_unlock (qse_spl_t* spl)
 	}
 	static QSE_INLINE void qse_spl_lock (qse_spl_t* spl) 
 	{
-		int x;
-		do
-		{
-			x = qse_spl_trylock(spl);
-		}
-		while (x);
+		while (!qse_spl_trylock(spl)) /* nothing */;
 	}
 	static QSE_INLINE void qse_spl_unlock (qse_spl_t* spl) 
 	{
 		__asm__ volatile (
 		#if 1
 			"lwsync\n" 
-		#else
+		#elif 0
 			"sync\n" 
+		#else
+			"eieio\n" 
 		#endif
 			:
 			:
diff --git a/qse/lib/awk/mod-math.c b/qse/lib/awk/mod-math.c
index 0e4ad845..929f5b45 100644
--- a/qse/lib/awk/mod-math.c
+++ b/qse/lib/awk/mod-math.c
@@ -35,7 +35,7 @@
 #include <math.h>
 #if defined(HAVE_QUADMATH_H)
 #	include <quadmath.h>
-#elif defined(QSE_USE_AWK_FLTMAX) && (QSE_AWK_SIZEOF_FLT_T == 16)
+#elif defined(QSE_USE_AWK_FLTMAX) && (QSE_AWK_SIZEOF_FLT_T == 16) && defined(QSE_FLTMAX_REQUIRE_QUADMATH)
 #	error QUADMATH.H NOT AVAILABLE or NOT COMPILABLE
 #endif
 
diff --git a/qse/lib/si/thr.c b/qse/lib/si/thr.c
index 78fd1cba..95329b3d 100644
--- a/qse/lib/si/thr.c
+++ b/qse/lib/si/thr.c
@@ -30,6 +30,10 @@
 #include <qse/cmn/time.h>
 #include <stdarg.h>
 
+#if defined(HAVE_UNISTD_H)
+#	include <unistd.h>
+#endif
+
 #if (!defined(__unix__) && !defined(__unix)) || defined(HAVE_PTHREAD)
 
 qse_thr_t* qse_thr_open (qse_mmgr_t* mmgr, qse_size_t xtnsize)
@@ -208,14 +212,24 @@ static int __create_thread (qse_thr_t* thr)
 
 	if (thr->__stacksize > 0)
 	{
-		if (pthread_attr_setstacksize (&attr, thr->__stacksize) != 0)
+		int x;
+		qse_size_t ss = thr->__stacksize;
+	#if defined(PTHREAD_STACK_MIN)
+		if (ss < PTHREAD_STACK_MIN) ss = PTHREAD_STACK_MIN;
+	#endif
+	#if defined(_SC_PAGESIZE)
+		/* some systems(e.g. darwin 8.11.0/macosx) require the size 
+		 * to be page size aligned. */
+		ss = QSE_ALIGNTO(ss, sysconf(_SC_PAGESIZE));
+	#endif
+		if ((x = pthread_attr_setstacksize(&attr, ss)) != 0)
 		{
 			pthread_attr_destroy (&attr);
 			return -1;
 		}
 	}
 
-	if (pthread_create (&thr->__handle, &attr, __thread_main, thr) != 0) 
+	if (pthread_create(&thr->__handle, &attr, __thread_main, thr) != 0) 
 	{
 		pthread_attr_destroy (&attr);
 		return -1;