diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index ced7ba263..f97f3ffe1 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,3 +1,8 @@
+2007-12-11  Corinna Vinschen  <corinna@vinschen.de>
+
+	* localtime.cc (tzset): Call tzsetwall only if it hasn't been
+	called before.
+
 2007-12-07  Corinna Vinschen  <corinna@vinschen.de>
 
 	* include/sys/cygwin.h: Include limits.h.
diff --git a/winsup/cygwin/localtime.cc b/winsup/cygwin/localtime.cc
index 1dab62793..a2f415f08 100644
--- a/winsup/cygwin/localtime.cc
+++ b/winsup/cygwin/localtime.cc
@@ -1476,7 +1476,8 @@ tzset P((void))
 	const char *	name = getenv("TZ");
 
 	if (name == NULL) {
-		tzsetwall();
+		if (!lcl_is_set)
+			tzsetwall();
 		return;
 	}