diff --git a/trunk/src/utest/srs_utest.hpp b/trunk/src/utest/srs_utest.hpp
index 22d0d70e2..bf2f26c8a 100644
--- a/trunk/src/utest/srs_utest.hpp
+++ b/trunk/src/utest/srs_utest.hpp
@@ -67,7 +67,7 @@ extern srs_utime_t _srs_tmp_timeout;
 
 // For init array data.
 #define HELPER_ARRAY_INIT(buf, sz, val) \
-    for (int i = 0; i < (int)sz; i++) (buf)[i]=val
+    memset(buf, val, sz)
 
 // Dump simple stream to string.
 #define HELPER_BUFFER2STR(io) \
diff --git a/trunk/src/utest/srs_utest_service.cpp b/trunk/src/utest/srs_utest_service.cpp
index b4e85c591..e93816eab 100644
--- a/trunk/src/utest/srs_utest_service.cpp
+++ b/trunk/src/utest/srs_utest_service.cpp
@@ -1379,6 +1379,7 @@ VOID TEST(TCPServerTest, ContextUtility)
 
     int base_size = 0;
     if (true) {
+        errno = 0;
         int size = 0; char buf[1024]; HELPER_ARRAY_INIT(buf, 1024, 0);
         ASSERT_TRUE(srs_log_header(buf, 1024, true, true, "SRS", "100", "Trace", &size));
         base_size = size;
@@ -1386,6 +1387,7 @@ VOID TEST(TCPServerTest, ContextUtility)
     }
 
     if (true) {
+        errno = 0;
         int size = 0; char buf[1024]; HELPER_ARRAY_INIT(buf, 1024, 0);
         ASSERT_TRUE(srs_log_header(buf, 1024, false, true, "SRS", "100", "Trace", &size));
         EXPECT_EQ(base_size, size);
@@ -1399,6 +1401,7 @@ VOID TEST(TCPServerTest, ContextUtility)
     }
 
     if (true) {
+        errno = 0;
         int size = 0; char buf[1024]; HELPER_ARRAY_INIT(buf, 1024, 0);
         ASSERT_TRUE(srs_log_header(buf, 1024, false, false, NULL, "100", "Trace", &size));
         EXPECT_EQ(base_size - 8, size);