diff --git a/include/payload.h b/include/payload.h
index b41bb113..8ae86e6e 100644
--- a/include/payload.h
+++ b/include/payload.h
@@ -55,6 +55,7 @@ public:
   void addButton(uint8_t value);
   void addSensor(uint8_t[]);
   void addTime(time_t value);
+  void addTimeDiff(int32_t value);
 
 #if (PAYLOAD_ENCODER == 1) // format plain
 
diff --git a/src/payload.cpp b/src/payload.cpp
index 8afd0b3b..ac310c55 100644
--- a/src/payload.cpp
+++ b/src/payload.cpp
@@ -16,7 +16,14 @@ uint8_t *PayloadConvert::getBuffer(void) { return buffer; }
 
 /* ---------------- plain format without special encoding ---------- */
 
-#if (PAYLOAD_ENCODER == 1)
+void PayloadConvert::addTimeDiff(int32_t value) {
+  buffer[cursor++] = (byte)((value & 0xFF000000) >> 24);
+  buffer[cursor++] = (byte)((value & 0x00FF0000) >> 16);
+  buffer[cursor++] = (byte)((value & 0x0000FF00) >> 8);
+  buffer[cursor++] = (byte)((value & 0x000000FF));
+}
+
+#if PAYLOAD_ENCODER == 1
 
 void PayloadConvert::addByte(uint8_t value) { buffer[cursor++] = (value); }
 
@@ -308,8 +315,8 @@ void PayloadConvert::writeBitmap(bool a, bool b, bool c, bool d, bool e, bool f,
 
 #elif ((PAYLOAD_ENCODER == 3) || (PAYLOAD_ENCODER == 4))
 
-void PayloadConvert::addByte(uint8_t value) { 
-  /* 
+void PayloadConvert::addByte(uint8_t value) {
+  /*
   not implemented
   */ }
 
@@ -486,4 +493,4 @@ void PayloadConvert::addTime(time_t value) {
 #endif
 }
 
-#endif
\ No newline at end of file
+#endif
diff --git a/src/timesync.cpp b/src/timesync.cpp
index ef50041d..2c5b5db0 100644
--- a/src/timesync.cpp
+++ b/src/timesync.cpp
@@ -240,7 +240,42 @@ void IRAM_ATTR setMyTime(uint32_t t_sec, uint16_t t_msec,
     CLOCKIRQ();            // fire clock pps, this advances time 1 sec
 #endif
 
-    setTime(time_to_set); // set the time on top of second
+    struct timeval tv;
+    struct timezone tz;
+    if(gettimeofday(&tv, &tz) != 0) {
+      ESP_LOGI(TAG, "ERROR gettimeofday");
+    }
+    struct timeval before = tv;
+
+    struct timeval now;
+    now.tv_sec = t_sec;
+    now.tv_usec = t_msec;
+    if(settimeofday(&tv, &tz) != 0) {
+      ESP_LOGE(TAG, "ERROR settimeofday");
+    }
+
+    struct timeval diff;
+    diff.tv_sec = now.tv_sec-before.tv_sec;
+    diff.tv_usec = now.tv_usec-before.tv_usec;
+
+    // sum up diff_s and diff_ms to one ms value
+    int32_t diff_s = diff.tv_sec;
+    int32_t diff_ms = diff.tv_usec/1000;
+    int32_t diff_ms_remain = diff_ms / 1000;
+    diff_s += diff_ms_remain;
+    diff_ms += -1000*diff_ms_remain;
+    if(diff_ms < 0) {
+      diff_s --;
+      diff_ms += 1000;
+    }
+    // cap diff at 24h (= 86,400s)
+    diff_s = diff_s % 86400;
+    int32_t timediff_ms = diff_s * 1000 + diff_ms;
+
+    // send diffTime
+    payload.reset();
+    payload.addTimeDiff(timediff_ms);
+    SendPayload(TIMEDIFFPORT, prio_high);
 
     timeSource = mytimesource; // set global variable
     timesyncer.attach(TIME_SYNC_INTERVAL * 60, timeSync);
@@ -264,4 +299,4 @@ void timesync_init() {
                           1);                   // CPU core
 }
 
-#endif
\ No newline at end of file
+#endif