diff --git a/CHANGELOG.md b/CHANGELOG.md
index c8fe4b61f..6c7b651d1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -23,6 +23,7 @@ All notable changes to this project will be documented in this file.
 - Correct Energy period display shortly after midnight by gominoa (#9536)
 - Rule handling of Var or Mem using text regression from v8.5.0.1 (#9540)
 - TuyaMcu energy display regression from v8.5.0.1 (#9547)
+- MQTT data corruption on ``MQTTLog 4`` (#9571)
 
 ## [9.0.0.1] - 20201010
 ### Added
diff --git a/tasmota/support.ino b/tasmota/support.ino
index 9e85168e1..462aec9e2 100644
--- a/tasmota/support.ino
+++ b/tasmota/support.ino
@@ -386,7 +386,7 @@ char* RemoveControlCharacter(char* p) {
       *write++ = ch;
     }
   }
-  if (write != p) { *write-- = '\0'; }
+  *write++ = '\0';
   return p;
 }
 
diff --git a/tasmota/xdrv_02_mqtt.ino b/tasmota/xdrv_02_mqtt.ino
index bee6eb941..ee39145c0 100644
--- a/tasmota/xdrv_02_mqtt.ino
+++ b/tasmota/xdrv_02_mqtt.ino
@@ -220,6 +220,12 @@ bool MqttPublishLib(const char* topic, bool retained)
   return result;
 }
 
+void MqttDumpData(char* topic, char* data, uint32_t data_len) {
+  char dump_data[data_len +1];
+  memcpy(dump_data, mqtt_data, sizeof(dump_data));  // Make another copy for removing optional control characters
+  AddLog_P2(LOG_LEVEL_DEBUG_MORE, PSTR(D_LOG_MQTT D_DATA_SIZE " %d, \"%s %s\""), data_len, topic, RemoveControlCharacter(dump_data));
+}
+
 void MqttDataHandler(char* mqtt_topic, uint8_t* mqtt_data, unsigned int data_len)
 {
 #ifdef USE_DEBUG_DRIVER
@@ -242,14 +248,12 @@ void MqttDataHandler(char* mqtt_topic, uint8_t* mqtt_data, unsigned int data_len
   char topic[TOPSZ];
   strlcpy(topic, mqtt_topic, sizeof(topic));
   mqtt_data[data_len] = 0;
-
   char data[data_len +1];
-
   memcpy(data, mqtt_data, sizeof(data));
-  AddLog_P2(LOG_LEVEL_DEBUG_MORE, PSTR(D_LOG_MQTT D_DATA_SIZE " %d, \"%s %s\""), data_len, topic, RemoveControlCharacter(data));
+
+//  AddLog_P2(LOG_LEVEL_DEBUG_MORE, PSTR(D_LOG_MQTT D_DATA_SIZE " %d, \"%s %s\""), data_len, topic, data);
 //  if (LOG_LEVEL_DEBUG_MORE <= seriallog_level) { Serial.println(data); }
-
-  memcpy(data, mqtt_data, sizeof(data));
+  MqttDumpData(topic, data, data_len);  // Use a function to save stack space used by dump_data
 
   // MQTT pre-processing
   XdrvMailbox.index = strlen(topic);