diff --git a/ChangeLog b/ChangeLog
index 7b527c2a9f..04d38b99e2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,7 +1,13 @@
+Mon Feb 15 17:42:20 2010  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* signal.c (USE_SIGALTSTACK): NetBSD can't use sigaltstack(2)
+	  with pthread.
+	  http://netbsd.gw.com/cgi-bin/man-cgi?sigaltstack++NetBSD-current
+
 Mon Feb 15 13:11:47 2010  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* array.c (rb_ary_push_m): use rb_ary_modify instead of
-	  rb_ary_modify_check.
+	  rb_ary_modify_check. This fixes regression due to r26632.
 
 Sun Feb 14 12:54:44 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
diff --git a/signal.c b/signal.c
index cbccf22419..3fe16337f0 100644
--- a/signal.c
+++ b/signal.c
@@ -419,7 +419,7 @@ static struct {
 #define sighandler_t sh_t
 #endif
 
-#if defined(SIGSEGV) && defined(HAVE_SIGALTSTACK) && defined(SA_SIGINFO)
+#if defined(SIGSEGV) && defined(HAVE_SIGALTSTACK) && defined(SA_SIGINFO) && !defined(__NetBSD__)
 #define USE_SIGALTSTACK
 #endif