diff --git a/pjlib/src/pj/os_timestamp_win32.c b/pjlib/src/pj/os_timestamp_win32.c
index 7cd391e37..63f624ca0 100644
--- a/pjlib/src/pj/os_timestamp_win32.c
+++ b/pjlib/src/pj/os_timestamp_win32.c
@@ -17,9 +17,23 @@
  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 
  */
 #include <pj/os.h>
+#include <pj/assert.h>
 #include <pj/errno.h>
+#include <pj/log.h>
 #include <windows.h>
 
+#define THIS_FILE   "os_timestamp_win32.c"
+
+
+#if 1
+#   define TRACE_(x)	    PJ_LOG(3,x)
+#else
+#   define TRACE_(x)	    ;
+#endif
+
+
+/////////////////////////////////////////////////////////////////////////////
+
 #if defined(PJ_TIMESTAMP_USE_RDTSC) && PJ_TIMESTAMP_USE_RDTSC!=0 && \
     defined(PJ_M_I386) && PJ_M_I386 != 0 && \
     defined(PJ_HAS_PENTIUM) && PJ_HAS_PENTIUM!=0 && \
@@ -94,9 +108,164 @@ PJ_DEF(pj_status_t) pj_get_timestamp_freq(pj_timestamp *freq)
     return PJ_SUCCESS;
 }
 
+/////////////////////////////////////////////////////////////////////////////
+
+#elif defined(PJ_TIMESTAMP_WIN32_USE_SAFE_QPC) && \
+         PJ_TIMESTAMP_WIN32_USE_SAFE_QPC!=0
+
+/* Use safe QueryPerformanceCounter.
+ * This implementation has some protection against bug in KB Q274323:
+ *   Performance counter value may unexpectedly leap forward
+ *   http://support.microsoft.com/default.aspx?scid=KB;EN-US;Q274323
+ *
+ * THIS SHOULD NOT BE USED YET AS IT DOESN'T HANDLE SYSTEM TIME
+ * CHANGE.
+ */
+
+static pj_timestamp g_ts_freq;
+static pj_timestamp g_ts_base;
+static pj_int64_t   g_time_base;
+
+PJ_DEF(pj_status_t) pj_get_timestamp(pj_timestamp *ts)
+{
+    enum { MAX_RETRY = 10 };
+    unsigned i;
+
+
+    /* pj_get_timestamp_freq() must have been called before.
+     * This is done when application called pj_init().
+     */
+    pj_assert(g_ts_freq.u64 != 0);
+
+    /* Retry QueryPerformanceCounter() until we're sure that the
+     * value returned makes sense.
+     */
+    i = 0;
+    do {
+	LARGE_INTEGER val;
+	pj_int64_t counter64, time64, diff;
+	pj_time_val time_now;
+
+	/* Retrieve the counter */
+	if (!QueryPerformanceCounter(&val))
+	    return PJ_RETURN_OS_ERROR(GetLastError());
+
+	/* Regardless of the goodness of the value, we should put
+	 * the counter here, because normally application wouldn't
+	 * check the error result of this function.
+	 */
+	ts->u64 = val.QuadPart;
+
+	/* Retrieve time */
+	pj_gettimeofday(&time_now);
+
+	/* Get the counter elapsed time in miliseconds */
+	counter64 = (val.QuadPart - g_ts_base.u64) * 1000 / g_ts_freq.u64;
+	
+	/* Get the time elapsed in miliseconds. 
+	 * We don't want to use PJ_TIME_VAL_MSEC() since it's using
+	 * 32bit calculation, which limits the maximum elapsed time
+	 * to around 49 days only.
+	 */
+	time64 = time_now.sec;
+	time64 = time64 * 1000 + time_now.msec;
+	//time64 = GetTickCount();
+
+	/* It's good if the difference between two clocks are within
+	 * some compile time constant (default: 20ms, which to allow
+	 * context switch happen between QueryPerformanceCounter and
+	 * pj_gettimeofday()).
+	 */
+	diff = (time64 - g_time_base) - counter64;
+	if (diff >= -20 && diff <= 20) {
+	    /* It's good */
+	    return PJ_SUCCESS;
+	}
+
+	++i;
+
+    } while (i < MAX_RETRY);
+
+    TRACE_((THIS_FILE, "QueryPerformanceCounter returned bad value"));
+    return PJ_ETIMEDOUT;
+}
+
+static pj_status_t init_performance_counter(void)
+{
+    LARGE_INTEGER val;
+    pj_time_val time_base;
+    pj_status_t status;
+
+    /* Get the frequency */
+    if (!QueryPerformanceFrequency(&val))
+	return PJ_RETURN_OS_ERROR(GetLastError());
+
+    g_ts_freq.u64 = val.QuadPart;
+
+    /* Get the base timestamp */
+    if (!QueryPerformanceCounter(&val))
+	return PJ_RETURN_OS_ERROR(GetLastError());
+
+    g_ts_base.u64 = val.QuadPart;
+
+
+    /* Get the base time */
+    status = pj_gettimeofday(&time_base);
+    if (status != PJ_SUCCESS)
+	return status;
+
+    /* Convert time base to 64bit value in msec */
+    g_time_base = time_base.sec;
+    g_time_base  = g_time_base * 1000 + time_base.msec;
+    //g_time_base = GetTickCount();
+
+    return PJ_SUCCESS;
+}
+
+PJ_DEF(pj_status_t) pj_get_timestamp_freq(pj_timestamp *freq)
+{
+    if (g_ts_freq.u64 == 0) {
+	enum { MAX_REPEAT = 10 };
+	unsigned i;
+	pj_status_t status;
+
+	/* Make unellegant compiler happy */
+	status = 0;
+
+	/* Repeat initializing performance counter until we're sure
+	 * the base timing is correct. It is possible that the system
+	 * returns bad counter during this initialization!
+	 */
+	for (i=0; i<MAX_REPEAT; ++i) {
+
+	    pj_timestamp dummy;
+
+	    /* Init base time */
+	    status = init_performance_counter();
+	    if (status != PJ_SUCCESS)
+		return status;
+
+	    /* Try the base time */
+	    status = pj_get_timestamp(&dummy);
+	    if (status == PJ_SUCCESS)
+		break;
+	}
+
+	if (status != PJ_SUCCESS)
+	    return status;
+    }
+
+    freq->u64 = g_ts_freq.u64;
+    return PJ_SUCCESS;
+}
+
+/////////////////////////////////////////////////////////////////////////////
+
 #else
+
 /*
  * Use QueryPerformanceCounter and QueryPerformanceFrequency.
+ * This should be the default implementation to be used on Windows.
  */
 PJ_DEF(pj_status_t) pj_get_timestamp(pj_timestamp *ts)
 {
@@ -120,5 +289,6 @@ PJ_DEF(pj_status_t) pj_get_timestamp_freq(pj_timestamp *freq)
     return PJ_SUCCESS;
 }
 
+
 #endif	/* PJ_TIMESTAMP_USE_RDTSC */