diff --git a/tasmota/support_tasmota.ino b/tasmota/support_tasmota.ino
index 671b4ad9d..e0a45ce77 100644
--- a/tasmota/support_tasmota.ino
+++ b/tasmota/support_tasmota.ino
@@ -1345,12 +1345,23 @@ void SerialInput(void)
 
   if (Settings.flag.mqtt_serial && serial_in_byte_counter && (millis() > (serial_polling_window + SERIAL_POLLING))) {  // CMND_SERIALSEND and CMND_SERIALLOG
     serial_in_buffer[serial_in_byte_counter] = 0;                                // Serial data completed
-    char hex_char[(serial_in_byte_counter * 2) + 2];
     bool assume_json = (!Settings.flag.mqtt_serial_raw && (serial_in_buffer[0] == '{'));
-    Response_P(PSTR("{\"" D_JSON_SERIALRECEIVED "\":%s%s%s}"),
-      (assume_json) ? "" : "\"",
-      (Settings.flag.mqtt_serial_raw) ? ToHex_P((unsigned char*)serial_in_buffer, serial_in_byte_counter, hex_char, sizeof(hex_char)) : serial_in_buffer,
-      (assume_json) ? "" : "\"");
+    
+    Response_P(PSTR("{\"" D_JSON_SERIALRECEIVED "\":"));
+    if (assume_json) {
+      ResponseAppend_P(serial_in_buffer);
+    } else {
+      ResponseAppend_P(PSTR("\""));
+      if (Settings.flag.mqtt_serial_raw) {
+        char hex_char[(serial_in_byte_counter * 2) + 2];
+        ResponseAppend_P(ToHex_P((unsigned char*)serial_in_buffer, serial_in_byte_counter, hex_char, sizeof(hex_char)));
+      } else {
+        ResponseAppend_P(EscapeJSONString(serial_in_buffer).c_str());
+      }
+      ResponseAppend_P(PSTR("\""));
+    }
+    ResponseAppend_P(PSTR("}"));
+
     MqttPublishPrefixTopic_P(RESULT_OR_TELE, PSTR(D_JSON_SERIALRECEIVED));
     XdrvRulesProcess();
     serial_in_byte_counter = 0;
diff --git a/tasmota/tasmota.h b/tasmota/tasmota.h
index 7434ff28e..fdace042c 100644
--- a/tasmota/tasmota.h
+++ b/tasmota/tasmota.h
@@ -129,7 +129,7 @@ const uint16_t FLOATSZ = 16;                // Max number of characters in float
 const uint16_t CMDSZ = 24;                  // Max number of characters in command
 const uint16_t TOPSZ = 151;                 // Max number of characters in topic string
 const uint16_t LOGSZ = 700;                 // Max number of characters in log
-const uint16_t MIN_MESSZ = 1040;            // Min number of characters in MQTT message (1000 - TOPSZ - 9 header bytes)
+const uint16_t MIN_MESSZ = 1040;            // Min number of characters in MQTT message (1200 - TOPSZ - 9 header bytes)
 
 const uint8_t SENSOR_MAX_MISS = 5;          // Max number of missed sensor reads before deciding it's offline
 
diff --git a/tasmota/xdrv_08_serial_bridge.ino b/tasmota/xdrv_08_serial_bridge.ino
index a713b5cfb..e50d4dd33 100644
--- a/tasmota/xdrv_08_serial_bridge.ino
+++ b/tasmota/xdrv_08_serial_bridge.ino
@@ -76,12 +76,23 @@ void SerialBridgeInput(void)
 
   if (serial_bridge_in_byte_counter && (millis() > (serial_bridge_polling_window + SERIAL_POLLING))) {
     serial_bridge_buffer[serial_bridge_in_byte_counter] = 0;                   // Serial data completed
-    char hex_char[(serial_bridge_in_byte_counter * 2) + 2];
     bool assume_json = (!serial_bridge_raw && (serial_bridge_buffer[0] == '{'));
-    Response_P(PSTR("{\"" D_JSON_SSERIALRECEIVED "\":%s%s%s}"),
-      (assume_json) ? "" : "\"",
-      (serial_bridge_raw) ? ToHex_P((unsigned char*)serial_bridge_buffer, serial_bridge_in_byte_counter, hex_char, sizeof(hex_char)) : serial_bridge_buffer,
-      (assume_json) ? "" : "\"");
+
+    Response_P(PSTR("{\"" D_JSON_SSERIALRECEIVED "\":"));
+    if (assume_json) {
+      ResponseAppend_P(serial_bridge_buffer);
+    } else {
+      ResponseAppend_P(PSTR("\""));
+      if (serial_bridge_raw) {
+        char hex_char[(serial_bridge_in_byte_counter * 2) + 2];
+        ResponseAppend_P(ToHex_P((unsigned char*)serial_bridge_buffer, serial_bridge_in_byte_counter, hex_char, sizeof(hex_char)));
+      } else {
+        ResponseAppend_P(EscapeJSONString(serial_bridge_buffer).c_str());
+      }
+      ResponseAppend_P(PSTR("\""));
+    }
+    ResponseAppend_P(PSTR("}"));
+
     MqttPublishPrefixTopic_P(RESULT_OR_TELE, PSTR(D_JSON_SSERIALRECEIVED));
     XdrvRulesProcess();
     serial_bridge_in_byte_counter = 0;