diff --git a/ChangeLog b/ChangeLog
index 3079f1c..b9e3926 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -332,7 +332,17 @@ Version 1.8.0
 Version 1.6.18
 *******************************************************************************
 
-2012-03-26 Yoichi NAKAYAMA <yoichi.nakayama(at)gmail.com>
+2012-04-05 Yoichi NAKAYAMA <yoichi.nakayama(at)gmail.com>
+
+	SF Bug Tracker id 3507819 - Use of thread-unsafe gmtime() in httpreadwrite.c
+
+	Submitted: zephyrus ( zephyrus00jp ) - 2012-03-18 06:31:00 PDT
+
+	Define http_gmtime_r and web_server_asctime_r and use it.
+	Those prefix are added since pthread for Win32 already
+	has macro gmtime_r and asctime_r.
+
+2012-04-05 Yoichi NAKAYAMA <yoichi.nakayama(at)gmail.com>
 
 	Fix type of local variable stopSock in RunMiniServer()
 
diff --git a/upnp/src/genlib/net/http/httpreadwrite.c b/upnp/src/genlib/net/http/httpreadwrite.c
index ab88c41..983a29c 100644
--- a/upnp/src/genlib/net/http/httpreadwrite.c
+++ b/upnp/src/genlib/net/http/httpreadwrite.c
@@ -164,6 +164,18 @@ static int private_connect(
 #endif /* UPNP_ENABLE_BLOCKING_TCP_CONNECTIONS */
 }
 
+#ifdef WIN32
+struct tm *http_gmtime_r(const time_t *clock, struct tm *result)
+{
+	if (clock == NULL || *clock < 0 || result == NULL)
+		return NULL;
+
+	/* gmtime in VC runtime is thread safe. */
+	*result = *gmtime(clock);
+	return result;
+}
+#endif
+
 static int get_hoststr(const char* url_str,
                        char **hoststr,
                        size_t *hostlen)
@@ -1466,6 +1478,7 @@ int http_MakeMessage(membuffer *buf, int http_major_version,
 	size_t length;
 	time_t *loc_time;
 	time_t curr_time;
+	struct tm date_storage;
 	struct tm *date;
 	const char *start_str;
 	const char *end_str;
@@ -1553,7 +1566,7 @@ int http_MakeMessage(membuffer *buf, int http_major_version,
 				loc_time = (time_t *)va_arg(argp, time_t *);
 			}
 			assert(loc_time);
-			date = gmtime(loc_time);
+			date = http_gmtime_r(loc_time, &date_storage);
 			if (date == NULL)
 				goto error_handler;
 			rc = snprintf(tempbuf, sizeof(tempbuf),
diff --git a/upnp/src/genlib/net/http/webserver.c b/upnp/src/genlib/net/http/webserver.c
index ea6b7c6..c0bb064 100644
--- a/upnp/src/genlib/net/http/webserver.c
+++ b/upnp/src/genlib/net/http/webserver.c
@@ -134,6 +134,20 @@ static const char *gMediaTypes[] = {
 #define NUM_MEDIA_TYPES       69
 #define NUM_HTTP_HEADER_NAMES 33
 
+#define ASCTIME_R_BUFFER_SIZE 26
+#ifdef WIN32
+static char *web_server_asctime_r(const struct tm *tm, char *buf)
+{
+	if (tm == NULL || buf == NULL)
+		return NULL;
+
+	asctime_s(buf, ASCTIME_R_BUFFER_SIZE, tm);
+	return buf;
+}
+#else
+#define web_server_asctime_r asctime_r
+#endif
+
 /* sorted by file extension; must have 'NUM_MEDIA_TYPES' extensions */
 static const char *gEncodedMediaTypes =
 	"aif\0" AUDIO_STR "aiff\0"
@@ -515,6 +529,8 @@ static int get_file_info(
 	FILE *fp;
 	int rc = 0;
 	time_t aux_LastModified;
+	struct tm date;
+	char buffer[ASCTIME_R_BUFFER_SIZE];
 
 	UpnpFileInfo_set_ContentType(info, NULL);
 	code = stat(filename, &s);
@@ -539,7 +555,7 @@ static int get_file_info(
 		"file info: %s, length: %lld, last_mod=%s readable=%d\n",
 		filename,
 		(long long)UpnpFileInfo_get_FileLength(info),
-		asctime(gmtime(&aux_LastModified)),
+		web_server_asctime_r(http_gmtime_r(&aux_LastModified, &date), buffer),
 		UpnpFileInfo_get_IsReadable(info));
 
 	return rc;
diff --git a/upnp/src/inc/httpreadwrite.h b/upnp/src/inc/httpreadwrite.h
index 79d16ff..8d80b27 100644
--- a/upnp/src/inc/httpreadwrite.h
+++ b/upnp/src/inc/httpreadwrite.h
@@ -49,6 +49,12 @@
 extern "C" {
 #endif
 
+#ifdef WIN32
+struct tm *http_gmtime_r(const time_t *clock, struct tm *result);
+#else
+#define http_gmtime_r gmtime_r
+#endif
+
 int http_CancelHttpGet(IN void *Handle);
 
 /*!