diff --git a/ChangeLog b/ChangeLog
index e62908ab03..fe8e6fc7c0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon Sep  1 02:55:15 2008  NAKAMURA Usaku  <usa@ruby-lang.org>
+
+	* strftime.c (rb_strftime): calc timezone offset by myself if system
+	  doesn't provide timezone info.
+
 Mon Sep  1 02:48:28 2008  Tanaka Akira  <akr@fsij.org>
 
 	* tool/transcode-tblgen.rb: change "illegal" to "invalid".
diff --git a/strftime.c b/strftime.c
index e559c05dd1..0f5214990f 100644
--- a/strftime.c
+++ b/strftime.c
@@ -477,6 +477,15 @@ rb_strftime(char *s, size_t maxsize, const char *format, const struct tm *timept
 #ifdef HAVE_GETTIMEOFDAY
 				gettimeofday(&tv, &zone);
 				off = -zone.tz_minuteswest;
+#else
+				/* no timezone info, then calc by myself */
+				{
+					struct tm utc;
+					time_t now;
+					time(&now);
+					utc = *gmtime(&now);
+					off = (now - mktime(&utc)) / 60;
+				}
 #endif
 #endif /* !HAVE_TIMEZONE */
 #endif /* !HAVE_TM_ZONE */