diff --git a/ChangeLog b/ChangeLog
index 23269bed4d..3761bd194f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Mon Apr 25 19:59:47 2011  Tajima, Akio <artonx@yahoo.co.jp>
+
+	* win32/win32.c (kill): accept 0 as pid, fixes #4596
+
 Mon Apr 25 16:43:45 2011  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* random.c (random_rand): remove unused variables.
diff --git a/win32/win32.c b/win32/win32.c
index 6dafecb079..ff3d33be75 100644
--- a/win32/win32.c
+++ b/win32/win32.c
@@ -3733,7 +3733,7 @@ kill(int pid, int sig)
     int ret = 0;
     DWORD err;
 
-    if (pid <= 0) {
+    if (pid < 0) {
 	errno = EINVAL;
 	return -1;
     }