diff --git a/ChangeLog b/ChangeLog
index 6f64a7e7b3..abcb212803 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Wed Feb 18 22:28:00 2009  NAKAMURA Usaku  <usa@ruby-lang.org>
+
+	* win32/win32.c (rb_w32_isatty): check whether fd is valid.
+
 Wed Feb 18 22:24:23 2009  NAKAMURA Usaku  <usa@ruby-lang.org>
 
 	* win32/win32.c (waitpid): fix bug of checking child slot.
diff --git a/version.h b/version.h
index 8fb27d9bb5..20ab6bb617 100644
--- a/version.h
+++ b/version.h
@@ -2,7 +2,7 @@
 #define RUBY_RELEASE_DATE "2009-02-18"
 #define RUBY_VERSION_CODE 187
 #define RUBY_RELEASE_CODE 20090218
-#define RUBY_PATCHLEVEL 126
+#define RUBY_PATCHLEVEL 127
 
 #define RUBY_VERSION_MAJOR 1
 #define RUBY_VERSION_MINOR 8
diff --git a/win32/win32.c b/win32/win32.c
index abe3949600..944ff3a931 100644
--- a/win32/win32.c
+++ b/win32/win32.c
@@ -4088,6 +4088,10 @@ rb_w32_unlink(const char *path)
 int
 rb_w32_isatty(int fd)
 {
+    // validate fd by using _get_osfhandle() because we cannot access _nhandle
+    if (_get_osfhandle(fd) == -1) {
+	return 0;
+    }
     if (!(_osfile(fd) & FOPEN)) {
 	errno = EBADF;
 	return 0;