diff --git a/ChangeLog b/ChangeLog
index fc116a717e..7fe337e536 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,16 @@
+Fri Feb 14 15:04:36 2014  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* thread_pthread.c (rb_thread_create_timer_thread): fix for platforms
+	  where PTHREAD_STACK_MIN is a dynamic value and not a compile-time
+	  constant.  [ruby-dev:47911] [Bug #9436]
+
+Fri Feb 14 15:04:36 2014  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* thread_pthread.c (rb_thread_create_timer_thread): expand timer
+	  thread stack size to get rid of segfault on FreeBSD/powerpc64.
+	  based on the patch by Steve Wills at [ruby-core:59923].
+	  [ruby-core:56590] [Bug #8783]
+
 Fri Feb 14 14:58:19 2014  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* eval.c (rb_mod_s_constants): return its own constants for other
diff --git a/thread_pthread.c b/thread_pthread.c
index 2cfceef936..9616cc2e38 100644
--- a/thread_pthread.c
+++ b/thread_pthread.c
@@ -1193,17 +1193,16 @@ rb_thread_create_timer_thread(void)
 
 	pthread_attr_init(&attr);
 #ifdef PTHREAD_STACK_MIN
-	if (PTHREAD_STACK_MIN < 4096 * 3) {
+	{
+	    const size_t min_size = (4096 * 4);
 	    /* Allocate the machine stack for the timer thread
-             * at least 12KB (3 pages).  FreeBSD 8.2 AMD64 causes
-             * machine stack overflow only with PTHREAD_STACK_MIN.
+	     * at least 16KB (4 pages).  FreeBSD 8.2 AMD64 causes
+	     * machine stack overflow only with PTHREAD_STACK_MIN.
 	     */
-	    pthread_attr_setstacksize(&attr,
-				      4096 * 3 + (THREAD_DEBUG ? BUFSIZ : 0));
-	}
-	else {
-	    pthread_attr_setstacksize(&attr,
-				      PTHREAD_STACK_MIN + (THREAD_DEBUG ? BUFSIZ : 0));
+	    size_t stack_size = PTHREAD_STACK_MIN; /* may be dynamic, get only once */
+	    if (stack_size < min_size) stack_size = min_size;
+	    if (THREAD_DEBUG) stack_size += BUFSIZ;
+	    pthread_attr_setstacksize(&attr, stack_size);
 	}
 #endif
 
diff --git a/version.h b/version.h
index 13684ce114..d76d9d9766 100644
--- a/version.h
+++ b/version.h
@@ -1,5 +1,5 @@
 #define RUBY_VERSION "1.9.3"
-#define RUBY_PATCHLEVEL 521
+#define RUBY_PATCHLEVEL 522
 
 #define RUBY_RELEASE_DATE "2014-02-14"
 #define RUBY_RELEASE_YEAR 2014