diff --git a/trunk/src/libs/srs_librtmp.cpp b/trunk/src/libs/srs_librtmp.cpp
index 3cdf9388a..84f61fc6f 100644
--- a/trunk/src/libs/srs_librtmp.cpp
+++ b/trunk/src/libs/srs_librtmp.cpp
@@ -2340,7 +2340,7 @@ int srs_human_print_rtmp_packet(char type, u_int32_t timestamp, char* data, int
 const char* srs_human_format_time()
 {
     struct timeval tv;
-    char buf[23];
+    static char buf[23];
     
     memset(buf, 0, sizeof(buf));