diff --git a/sonoff/_changelog.ino b/sonoff/_changelog.ino
index 8b5af65ce..c3d1e4c6a 100644
--- a/sonoff/_changelog.ino
+++ b/sonoff/_changelog.ino
@@ -1,5 +1,6 @@
 /* 6.2.0.1 20180902
  * Fix possible ambiguity on command parameters if StateText contains numbers only (#3656)
+ * Fix possible exception due to buffer overflow (#3659)
  *
  * 6.2.0 20180901
  * Allow user override of define MAX_RULE_VARS and MAX_RULE_TIMERS (#3561)
diff --git a/sonoff/sonoff.ino b/sonoff/sonoff.ino
index 254f88184..93ffbda01 100755
--- a/sonoff/sonoff.ino
+++ b/sonoff/sonoff.ino
@@ -442,7 +442,7 @@ void MqttDataHandler(char* topic, byte* data, unsigned int data_len)
 
   ShowFreeMem(PSTR("MqttDataHandler"));
 
-  strncpy(topicBuf, topic, sizeof(topicBuf));
+  strlcpy(topicBuf, topic, sizeof(topicBuf));
   for (i = 0; i < data_len; i++) {
     if (!isspace(data[i])) break;
   }
diff --git a/sonoff/support.ino b/sonoff/support.ino
index eed4146c2..8aaeabf88 100644
--- a/sonoff/support.ino
+++ b/sonoff/support.ino
@@ -143,7 +143,7 @@ char* subStr(char* dest, char* str, const char *delim, int index)
   int i;
 
   // Since strtok consumes the first arg, make a copy
-  strncpy(dest, str, strlen(str));
+  strlcpy(dest, str, strlen(str));
   for (i = 1, act = dest; i <= index; i++, act = NULL) {
     sub = strtok_r(act, delim, &ptr);
     if (sub == NULL) break;
@@ -157,7 +157,7 @@ double CharToDouble(char *str)
   // simple ascii to double, because atof or strtod are too large
   char strbuf[24];
 
-  strcpy(strbuf, str);
+  strlcpy(strbuf, str, sizeof(strbuf));
   char *pt;
   double left = atoi(strbuf);
   double right = 0;
diff --git a/sonoff/xdrv_02_webserver.ino b/sonoff/xdrv_02_webserver.ino
index c919c8f43..91c01eeae 100644
--- a/sonoff/xdrv_02_webserver.ino
+++ b/sonoff/xdrv_02_webserver.ino
@@ -372,8 +372,8 @@ long ajax_token = 1;
 static void WebGetArg(const char* arg, char* out, size_t max)
 {
   String s = WebServer->arg(arg);
-  strncpy(out, s.c_str(), max);
-  out[max-1] = '\0';  // Ensure terminating NUL
+  strlcpy(out, s.c_str(), max);
+//  out[max-1] = '\0';  // Ensure terminating NUL
 }
 
 void ShowWebSource(int source)
diff --git a/sonoff/xdsp_01_lcd.ino b/sonoff/xdsp_01_lcd.ino
index 9d4a5d396..bfc0b3536 100644
--- a/sonoff/xdsp_01_lcd.ino
+++ b/sonoff/xdsp_01_lcd.ino
@@ -107,7 +107,7 @@ void LcdCenter(byte row, char* txt)
   line[Settings.display_cols[0]] = 0;
   len = strlen(txt);
   offset = (len < Settings.display_cols[0]) ? offset = (Settings.display_cols[0] - len) / 2 : 0;
-  strncpy(line +offset, txt, len);
+  strlcpy(line +offset, txt, len);
   lcd->setCursor(0, row);
   lcd->print(line);
 }
diff --git a/sonoff/xsns_01_counter.ino b/sonoff/xsns_01_counter.ino
index 069d5b3e7..b5822cac7 100644
--- a/sonoff/xsns_01_counter.ino
+++ b/sonoff/xsns_01_counter.ino
@@ -111,7 +111,7 @@ void CounterShow(boolean json)
         }
         header++;
         snprintf_P(mqtt_data, sizeof(mqtt_data), PSTR("%s%s\"C%d\":%s"), mqtt_data, stemp, i +1, counter);
-        strcpy(stemp, ",");
+        strlcpy(stemp, ",", sizeof(stemp));
 #ifdef USE_DOMOTICZ
         if ((0 == tele_period) && (1 == dsxflg)) {
           DomoticzSensor(DZ_COUNT, RtcSettings.pulse_counter[i]);
diff --git a/sonoff/xsns_05_ds18x20_legacy.ino b/sonoff/xsns_05_ds18x20_legacy.ino
index 156312104..03754bbe1 100644
--- a/sonoff/xsns_05_ds18x20_legacy.ino
+++ b/sonoff/xsns_05_ds18x20_legacy.ino
@@ -186,7 +186,7 @@ void Ds18x20Show(boolean json)
         dsxflg++;
         snprintf_P(mqtt_data, sizeof(mqtt_data), PSTR("%s%s\"DS%d\":{\"" D_JSON_TYPE "\":\"%s\",\"" D_JSON_ADDRESS "\":\"%s\",\"" D_JSON_TEMPERATURE "\":%s}"),
           mqtt_data, stemp, i +1, ds18x20_types, Ds18x20Addresses(i).c_str(), temperature);
-        strcpy(stemp, ",");
+        strlcpy(stemp, ",", sizeof(stemp));
 #ifdef USE_DOMOTICZ
         if ((0 == tele_period) && (1 == dsxflg)) {
           DomoticzSensor(DZ_TEMP, temperature);
diff --git a/sonoff/xsns_12_ads1115.ino b/sonoff/xsns_12_ads1115.ino
index f1279a732..bcfb6dfad 100644
--- a/sonoff/xsns_12_ads1115.ino
+++ b/sonoff/xsns_12_ads1115.ino
@@ -191,7 +191,7 @@ void Ads1115Show(boolean json)
         }
         dsxflg++;
         snprintf_P(mqtt_data, sizeof(mqtt_data), PSTR("%s%s\"A%d\":%d"), mqtt_data, stemp, i, adc_value);
-        strcpy(stemp, ",");
+        strlcpy(stemp, ",", sizeof(stemp));
 #ifdef USE_WEBSERVER
       } else {
         snprintf_P(mqtt_data, sizeof(mqtt_data), HTTP_SNS_ANALOG, mqtt_data, "ADS1115", i, adc_value);
diff --git a/sonoff/xsns_12_ads1115_i2cdev.ino b/sonoff/xsns_12_ads1115_i2cdev.ino
index d3748ec7a..588a37ac5 100644
--- a/sonoff/xsns_12_ads1115_i2cdev.ino
+++ b/sonoff/xsns_12_ads1115_i2cdev.ino
@@ -111,7 +111,7 @@ void Ads1115Show(boolean json)
         }
         dsxflg++;
         snprintf_P(mqtt_data, sizeof(mqtt_data), PSTR("%s%s\"A%d\":%d"), mqtt_data, stemp, i, adc_value);
-        strcpy(stemp, ",");
+        strlcpy(stemp, ",", sizeof(stemp));
 #ifdef USE_WEBSERVER
       } else {
         snprintf_P(mqtt_data, sizeof(mqtt_data), HTTP_SNS_ANALOG, mqtt_data, "ADS1115", i, adc_value);