diff --git a/ChangeLog b/ChangeLog
index c5b45722fc..d8d84b7ac9 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Tue Aug 30 09:53:59 2011  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
+
+	* cont.c (fiber_entry): fix stack allocation failure on Debian
+	  GNU/kFreeBSD.
+	  Patch by Lucas Nussbaum <lucas at lucas-nussbaum dot net>.
+	  [Bug #5241] [ruby-core:39147]
+
 Tue Aug 30 09:52:29 2011  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
 
 	* backport r33117 from trunk.
diff --git a/cont.c b/cont.c
index d44afaa447..4f30e50831 100644
--- a/cont.c
+++ b/cont.c
@@ -520,8 +520,9 @@ fiber_entry(void *arg)
 /*
  * FreeBSD require a first (i.e. addr) argument of mmap(2) is not NULL
  * if MAP_STACK is passed.
+ * http://www.FreeBSD.org/cgi/query-pr.cgi?pr=158755
  */
-#if defined(MAP_STACK) && !defined(__FreeBSD__)
+#if defined(MAP_STACK) && !defined(__FreeBSD__) && !defined(__FreeBSD_kernel__)
 #define FIBER_STACK_FLAGS (MAP_PRIVATE | MAP_ANON | MAP_STACK)
 #else
 #define FIBER_STACK_FLAGS (MAP_PRIVATE | MAP_ANON)