diff --git a/ChangeLog b/ChangeLog
index f34a2e2486..94bdaa0605 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Fri Oct 14 22:05:45 2005  NAKAMURA Usaku  <usa@ruby-lang.org>
+
+	* win32/win32.c (ioctl): should set errno.
+
 Fri Oct 14 16:39:37 2005  GOTOU Yuuzou  <gotoyuzo@notwork.org>
 
 	* lib/webrick/config.rb (Config::FileHandler): :UserDir should be nil.
diff --git a/win32/win32.c b/win32/win32.c
index b16f595d55..fc6b587b20 100644
--- a/win32/win32.c
+++ b/win32/win32.c
@@ -1839,6 +1839,7 @@ setgid(rb_gid_t gid)
 int
 ioctl(int i, int u, ...)
 {
+    errno = EINVAL;
     return -1;
 }