diff --git a/trunk/src/kernel/srs_kernel_utility.cpp b/trunk/src/kernel/srs_kernel_utility.cpp
index 085d74331..d0f19d86c 100644
--- a/trunk/src/kernel/srs_kernel_utility.cpp
+++ b/trunk/src/kernel/srs_kernel_utility.cpp
@@ -122,11 +122,14 @@ srs_utime_t srs_get_system_startup_time()
     return _srs_system_time_startup_time;
 }
 
+// For utest to mock it.
+_srs_gettimeofday_t _srs_gettimeofday = ::gettimeofday;
+
 srs_utime_t srs_update_system_time()
 {
     timeval now;
     
-    if (gettimeofday(&now, NULL) < 0) {
+    if (_srs_gettimeofday(&now, NULL) < 0) {
         srs_warn("gettimeofday failed, ignore");
         return -1;
     }
diff --git a/trunk/src/kernel/srs_kernel_utility.hpp b/trunk/src/kernel/srs_kernel_utility.hpp
index 56bb78771..99a3fdc6a 100644
--- a/trunk/src/kernel/srs_kernel_utility.hpp
+++ b/trunk/src/kernel/srs_kernel_utility.hpp
@@ -161,5 +161,9 @@ extern int srs_chunk_header_c0(int perfer_cid, uint32_t timestamp, int32_t paylo
 // @return the size of header. 0 if cache not enough.
 extern int srs_chunk_header_c3(int perfer_cid, uint32_t timestamp, char* cache, int nb_cache);
 
+// For utest to mock it.
+#include <sys/time.h>
+typedef int (*_srs_gettimeofday_t)(struct timeval* tv, struct timezone* tz);
+
 #endif
 
diff --git a/trunk/src/utest/srs_utest_kernel.cpp b/trunk/src/utest/srs_utest_kernel.cpp
index 1898c533a..f3d580861 100644
--- a/trunk/src/utest/srs_utest_kernel.cpp
+++ b/trunk/src/utest/srs_utest_kernel.cpp
@@ -3597,6 +3597,37 @@ VOID TEST(KernelUtilityTest, CoverBitsBufferAll)
     }
 }
 
+extern _srs_gettimeofday_t _srs_gettimeofday;
+int mock_gettimeofday(struct timeval* /*tp*/, struct timezone* /*tzp*/) {
+	return -1;
+}
+
+class MockTime
+{
+private:
+	_srs_gettimeofday_t ot;
+public:
+	MockTime(_srs_gettimeofday_t t = NULL) {
+		ot = _srs_gettimeofday;
+		if (t) {
+			_srs_gettimeofday = t;
+		}
+	}
+	virtual ~MockTime() {
+		if (ot) {
+			_srs_gettimeofday = ot;
+		}
+	}
+};
+
+VOID TEST(KernelUtilityTest, CoverTimeSpecial)
+{
+	if (true) {
+		MockTime _mt(mock_gettimeofday);
+		EXPECT_TRUE(-1 == srs_update_system_time());
+	}
+}
+
 extern int64_t _srs_system_time_startup_time;
 extern int64_t _srs_system_time_us_cache;
 extern int av_toupper(int c);