diff --git a/code/espurna/analog.ino b/code/espurna/analog.ino
index 18c66438..1c8f1280 100644
--- a/code/espurna/analog.ino
+++ b/code/espurna/analog.ino
@@ -21,7 +21,7 @@ void analogSetup() {
     pinMode(ANALOG_PIN, INPUT);
 
     apiRegister(ANALOG_TOPIC, ANALOG_TOPIC, [](char * buffer, size_t len) {
-        snprintf(buffer, len, "%d", getAnalog());
+        snprintf_P(buffer, len, PSTR("%d"), getAnalog());
     });
 
 }
diff --git a/code/espurna/button.ino b/code/espurna/button.ino
index d0a8efcc..36eefada 100644
--- a/code/espurna/button.ino
+++ b/code/espurna/button.ino
@@ -25,7 +25,7 @@ std::vector<button_t> _buttons;
 void buttonMQTT(unsigned char id, uint8_t event) {
     if (id >= _buttons.size()) return;
     char payload[2];
-    sprintf(payload, "%d", event);
+    sprintf_P(payload, PSTR("%d"), event);
     mqttSend(MQTT_TOPIC_BUTTON, id, payload);
 }
 #endif
diff --git a/code/espurna/config/arduino.h b/code/espurna/config/arduino.h
index 11bcea82..fe1b830c 100644
--- a/code/espurna/config/arduino.h
+++ b/code/espurna/config/arduino.h
@@ -49,7 +49,6 @@
 //#define ENABLE_DOMOTICZ       0
 //#define ENABLE_DS18B20        1
 //#define ENABLE_EMON           1
-//#define ENABLE_HLW8012        1
 //#define ENABLE_I2C            1
 //#define ENABLE_INFLUXDB       0
 //#define ENABLE_FAUXMO         0
diff --git a/code/espurna/config/general.h b/code/espurna/config/general.h
index b22449a7..bb9334f2 100644
--- a/code/espurna/config/general.h
+++ b/code/espurna/config/general.h
@@ -33,7 +33,7 @@
 // General debug options and macros
 #define DEBUG_MESSAGE_MAX_LENGTH    80
 
-#if ENABLE_SERIAL_DEBUG | ENABLE_UDP_DEBUG
+#if (ENABLE_SERIAL_DEBUG==1) || (ENABLE_UDP_DEBUG==1)
     #define DEBUG_MSG(...) debugSend(__VA_ARGS__)
     #define DEBUG_MSG_P(...) debugSend_P(__VA_ARGS__)
 #endif
@@ -321,7 +321,9 @@ PROGMEM const char* const custom_reset_string[] = {
 // I2C
 // -----------------------------------------------------------------------------
 
+#ifndef ENABLE_I2C
 #define ENABLE_I2C              0           // I2C enabled
+#endif
 #define I2C_SDA_PIN             4           // SDA GPIO
 #define I2C_SCL_PIN             14          // SCL GPIO
 #define I2C_CLOCK_STRETCH_TIME  200         // BRZO clock stretch time
diff --git a/code/espurna/config/hardware.h b/code/espurna/config/hardware.h
index 8ebaa4fe..cd389e2e 100644
--- a/code/espurna/config/hardware.h
+++ b/code/espurna/config/hardware.h
@@ -84,6 +84,7 @@
     #define LED1_PIN_INVERSE    0
 
     // HLW8012
+    #define ENABLE_HLW8012      1
     #define HLW8012_SEL_PIN     2
     #define HLW8012_CF1_PIN     13
     #define HLW8012_CF_PIN      14
@@ -246,6 +247,7 @@
     #define LED1_PIN_INVERSE    0
 
     // HLW8012
+    #define ENABLE_HLW8012      1
     #define HLW8012_SEL_PIN     5
     #define HLW8012_CF1_PIN     13
     #define HLW8012_CF_PIN      14
diff --git a/code/espurna/dht.ino b/code/espurna/dht.ino
index 67927bf9..9c455f4a 100644
--- a/code/espurna/dht.ino
+++ b/code/espurna/dht.ino
@@ -34,7 +34,7 @@ void dhtSetup() {
         dtostrf(_dhtTemperature, len-1, 1, buffer);
     });
     apiRegister(DHT_HUMIDITY_TOPIC, DHT_HUMIDITY_TOPIC, [](char * buffer, size_t len) {
-        snprintf(buffer, len, "%d", _dhtHumidity);
+        snprintf_P(buffer, len, PSTR("%d"), _dhtHumidity);
     });
 }
 
@@ -88,7 +88,7 @@ void dhtLoop() {
                     status = HUMIDITY_DRY;
                 }
                 char buffer[2];
-                sprintf(buffer, "%d", status);
+                sprintf_P(buffer, PSTR("%d"), status);
                 domoticzSend("dczHumIdx", humidity, buffer);
             }
             #endif
diff --git a/code/espurna/domoticz.ino b/code/espurna/domoticz.ino
index a093a72f..cd870ae6 100644
--- a/code/espurna/domoticz.ino
+++ b/code/espurna/domoticz.ino
@@ -84,13 +84,13 @@ template<typename T> void domoticzSend(const char * key, T nvalue) {
 void domoticzSendRelay(unsigned int relayID) {
     if (!_dczEnabled) return;
     char buffer[15];
-    sprintf(buffer, "dczRelayIdx%d", relayID);
+    sprintf_P(buffer, PSTR("dczRelayIdx%d"), relayID);
     domoticzSend(buffer, relayStatus(relayID) ? "1" : "0");
 }
 
 int domoticzIdx(unsigned int relayID) {
     char buffer[15];
-    sprintf(buffer, "dczRelayIdx%d", relayID);
+    sprintf_P(buffer, PSTR("dczRelayIdx%d"), relayID);
     return getSetting(buffer).toInt();
 }
 
diff --git a/code/espurna/emon.ino b/code/espurna/emon.ino
index 94f042d1..dd5348c8 100644
--- a/code/espurna/emon.ino
+++ b/code/espurna/emon.ino
@@ -113,7 +113,7 @@ void powerMonitorSetup() {
 
     apiRegister(EMON_APOWER_TOPIC, EMON_APOWER_TOPIC, [](char * buffer, size_t len) {
         if (_emonReady) {
-            snprintf(buffer, len, "%d", _emonPower);
+            snprintf_P(buffer, len, PSTR("%d"), _emonPower);
         } else {
             buffer = NULL;
         }
@@ -191,11 +191,11 @@ void powerMonitorLoop() {
             #if ENABLE_DOMOTICZ
             {
                 char buffer[20];
-                snprintf(buffer, 20, "%d;%s", _emonPower, String(energy_delta, 3).c_str());
+                snprintf_P(buffer, 20, PSTR("%d;%s"), _emonPower, String(energy_delta, 3).c_str());
                 domoticzSend("dczPowIdx", 0, buffer);
-                snprintf(buffer, 20, "%s", String(energy_delta, 3).c_str());
+                snprintf_P(buffer, 20, PSTR("%s"), String(energy_delta, 3).c_str());
                 domoticzSend("dczEnergyIdx", 0, buffer);
-                snprintf(buffer, 20, "%s", String(_emonCurrent, 3).c_str());
+                snprintf_P(buffer, 20, PSTR("%s"), String(_emonCurrent, 3).c_str());
                 domoticzSend("dczCurrentIdx", 0, buffer);
             }
             #endif
diff --git a/code/espurna/espurna.ino b/code/espurna/espurna.ino
index 1143e031..acaec099 100644
--- a/code/espurna/espurna.ino
+++ b/code/espurna/espurna.ino
@@ -28,7 +28,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 String getIdentifier() {
     char identifier[20];
-    sprintf(identifier, "%s_%06X", DEVICE, ESP.getChipId());
+    sprintf_P(identifier, PSTR("%s_%06X"), DEVICE, ESP.getChipId());
     return String(identifier);
 }
 
diff --git a/code/espurna/hlw8012.ino b/code/espurna/hlw8012.ino
index 0a23926f..d3faf45a 100644
--- a/code/espurna/hlw8012.ino
+++ b/code/espurna/hlw8012.ino
@@ -160,7 +160,7 @@ void hlw8012Setup() {
     // API definitions
     apiRegister(HLW8012_POWER_TOPIC, HLW8012_POWER_TOPIC, [](char * buffer, size_t len) {
         if (_hlwReady) {
-            snprintf(buffer, len, "%d", _hlwPower);
+            snprintf_P(buffer, len, PSTR("%d"), _hlwPower);
         } else {
             buffer = NULL;
         }
@@ -174,7 +174,7 @@ void hlw8012Setup() {
     });
     apiRegister(HLW8012_VOLTAGE_TOPIC, HLW8012_VOLTAGE_TOPIC, [](char * buffer, size_t len) {
         if (_hlwReady) {
-            snprintf(buffer, len, "%d", _hlwVoltage);
+            snprintf_P(buffer, len, PSTR("%d"), _hlwVoltage);
         } else {
             buffer = NULL;
         }
@@ -295,13 +295,13 @@ void hlw8012Loop() {
             #if ENABLE_DOMOTICZ
             {
                 char buffer[20];
-                snprintf(buffer, 20, "%d;%s", _hlwPower, String(energy_delta, 3).c_str());
+                snprintf_P(buffer, 20, PSTR("%d;%s"), _hlwPower, String(energy_delta, 3).c_str());
                 domoticzSend("dczPowIdx", 0, buffer);
-                snprintf(buffer, 20, "%s", String(energy_delta, 3).c_str());
+                snprintf_P(buffer, 20, PSTR("%s"), String(energy_delta, 3).c_str());
                 domoticzSend("dczEnergyIdx", 0, buffer);
-                snprintf(buffer, 20, "%d", _hlwVoltage);
+                snprintf_P(buffer, 20, PSTR("%d"), _hlwVoltage);
                 domoticzSend("dczVoltIdx", 0, buffer);
-                snprintf(buffer, 20, "%s", String(_hlwCurrent).c_str());
+                snprintf_P(buffer, 20, PSTR("%s"), String(_hlwCurrent).c_str());
                 domoticzSend("dczCurrentIdx", 0, buffer);
             }
             #endif
diff --git a/code/espurna/influxdb.ino b/code/espurna/influxdb.ino
index f19e5add..82ed09fb 100644
--- a/code/espurna/influxdb.ino
+++ b/code/espurna/influxdb.ino
@@ -19,17 +19,17 @@ template<typename T> bool influxDBSend(const char * topic, T payload) {
     if (!influxDBEnabled) return true;
     if (!wifiConnected() || (WiFi.getMode() != WIFI_STA)) return true;
 
-    DEBUG_MSG_P(("[INFLUXDB] Sending\n"));
+    DEBUG_MSG("[INFLUXDB] Sending\n");
 
     _influxClient.setTimeout(2);
     if (!_influxClient.connect(getSetting("idbHost").c_str(), getSetting("idbPort", INFLUXDB_PORT).toInt())) {
-        DEBUG_MSG_P(("[INFLUXDB] Connection failed\n"));
+        DEBUG_MSG("[INFLUXDB] Connection failed\n");
         return false;
     }
 
     char data[128];
     sprintf(data, "%s,device=%s value=%s", topic, getSetting("hostname").c_str(), String(payload).c_str());
-    DEBUG_MSG_P(("[INFLUXDB] Data: %s\n"), data);
+    DEBUG_MSG("[INFLUXDB] Data: %s\n", data);
 
     char request[256];
     sprintf(request, "POST /write?db=%s&u=%s&p=%s HTTP/1.1\r\nHost: %s:%d\r\nContent-Length: %d\r\n\r\n%s",
@@ -45,7 +45,7 @@ template<typename T> bool influxDBSend(const char * topic, T payload) {
     }
 
     _influxClient.stop();
-    DEBUG_MSG_P(("[INFLUXDB] Sent failed\n"));
+    DEBUG_MSG("[INFLUXDB] Sent failed\n");
     while (_influxClient.connected()) delay(0);
     return false;
 
diff --git a/code/espurna/led.ino b/code/espurna/led.ino
index cb922779..b687cf12 100644
--- a/code/espurna/led.ino
+++ b/code/espurna/led.ino
@@ -64,7 +64,7 @@ void ledMQTTCallback(unsigned int type, const char * topic, const char * payload
 
     if (type == MQTT_CONNECT_EVENT) {
         char buffer[strlen(MQTT_TOPIC_LED) + 3];
-        sprintf(buffer, "%s/+", MQTT_TOPIC_LED);
+        sprintf_P(buffer, PSTR("%s/+"), MQTT_TOPIC_LED);
         mqttSubscribe(buffer);
     }
 
diff --git a/code/espurna/light.ino b/code/espurna/light.ino
index 2ceb850d..18e1df1e 100644
--- a/code/espurna/light.ino
+++ b/code/espurna/light.ino
@@ -133,7 +133,7 @@ void _toRGB(char * rgb, size_t len, bool applyBrightness) {
     value <<= 8;
     value += _channels[2].value * b;
 
-    snprintf(rgb, len, "#%06X", value);
+    snprintf_P(rgb, len, PSTR("#%06X"), value);
 
 }
 
@@ -293,7 +293,7 @@ void _lightMQTTCallback(unsigned int type, const char * topic, const char * payl
         }
 
         char buffer[strlen(MQTT_TOPIC_CHANNEL) + 3];
-        sprintf(buffer, "%s/+", MQTT_TOPIC_CHANNEL);
+        sprintf_P(buffer, PSTR("%s/+"), MQTT_TOPIC_CHANNEL);
         mqttSubscribe(buffer);
 
     }
@@ -370,14 +370,14 @@ void lightMQTT() {
         mqttSend(MQTT_TOPIC_COLOR, buffer);
 
         // Brightness
-        sprintf(buffer, "%d", _brightness);
+        sprintf_P(buffer, PSTR("%d"), _brightness);
         mqttSend(MQTT_TOPIC_BRIGHTNESS, buffer);
 
     }
 
     // Channels
     for (unsigned int i=0; i < _channels.size(); i++) {
-        sprintf(buffer, "%d", _channels[i].value);
+        sprintf_P(buffer, PSTR("%d"), _channels[i].value);
         mqttSend(MQTT_TOPIC_CHANNEL, i, buffer);
     }
 
@@ -476,7 +476,7 @@ void _lightAPISetup() {
 
         apiRegister(MQTT_TOPIC_BRIGHTNESS, MQTT_TOPIC_BRIGHTNESS,
             [](char * buffer, size_t len) {
-    			snprintf(buffer, len, "%d", _brightness);
+    			snprintf_P(buffer, len, PSTR("%d"), _brightness);
             },
             [](const char * payload) {
                 lightBrightness(atoi(payload));
@@ -505,14 +505,14 @@ void _lightAPISetup() {
     for (unsigned int id=0; id<lightChannels(); id++) {
 
         char url[15];
-        sprintf(url, "%s/%d", MQTT_TOPIC_CHANNEL, id);
+        sprintf_P(url, PSTR("%s/%d"), MQTT_TOPIC_CHANNEL, id);
 
         char key[10];
-        sprintf(key, "%s%d", MQTT_TOPIC_CHANNEL, id);
+        sprintf_P(key, PSTR("%s%d"), MQTT_TOPIC_CHANNEL, id);
 
         apiRegister(url, key,
             [id](char * buffer, size_t len) {
-				snprintf(buffer, len, "%d", lightChannel(id));
+				snprintf_P(buffer, len, PSTR("%d"), lightChannel(id));
             },
             [id](const char * payload) {
                 lightChannel(id, atoi(payload));
diff --git a/code/espurna/mqtt.ino b/code/espurna/mqtt.ino
index 55b62d10..a4f94d0a 100644
--- a/code/espurna/mqtt.ino
+++ b/code/espurna/mqtt.ino
@@ -129,7 +129,7 @@ void mqttSend(const char * topic, const char * message) {
 
 void mqttSend(const char * topic, unsigned int index, const char * message, bool force) {
     char buffer[strlen(topic)+5];
-    sprintf(buffer, "%s/%d", topic, index);
+    sprintf_P(buffer, PSTR("%s/%d"), topic, index);
     mqttSend(buffer, message, force);
 }
 
diff --git a/code/espurna/ntp.ino b/code/espurna/ntp.ino
index f42469e7..7515c7ab 100644
--- a/code/espurna/ntp.ino
+++ b/code/espurna/ntp.ino
@@ -39,7 +39,7 @@ String ntpDateTime() {
     int month = value.substring(12, 14).toInt();
     int year = value.substring(15, 19).toInt();
     char buffer[20];
-    sprintf(buffer, "%04d/%02d/%02dT%02d:%02d:%02d", year, month, day, hour, minute, second);
+    sprintf_P(buffer, PSTR("%04d/%02d/%02dT%02d:%02d:%02d"), year, month, day, hour, minute, second);
     return String(buffer);
 }
 
diff --git a/code/espurna/relay.ino b/code/espurna/relay.ino
index 4b4d7944..1357eb57 100644
--- a/code/espurna/relay.ino
+++ b/code/espurna/relay.ino
@@ -123,15 +123,15 @@ void relayPulseMode(unsigned int value, bool report) {
     /*
     if (report) {
         char topic[strlen(MQTT_TOPIC_RELAY) + 10];
-        sprintf(topic, "%s/pulse", MQTT_TOPIC_RELAY);
+        sprintf_P(topic, PSTR("%s/pulse"), MQTT_TOPIC_RELAY);
         char value[2];
-        sprintf(value, "%d", value);
+        sprintf_P(value, PSTR("%d"), value);
         mqttSend(topic, value);
     }
     */
 
     char message[20];
-    sprintf(message, "{\"relayPulseMode\": %d}", value);
+    sprintf_P(message, PSTR("{\"relayPulseMode\": %d}"), value);
     wsSend(message);
 
 }
@@ -299,14 +299,14 @@ void relaySetupAPI() {
     for (unsigned int relayID=0; relayID<relayCount(); relayID++) {
 
         char url[15];
-        sprintf(url, "%s/%d", MQTT_TOPIC_RELAY, relayID);
+        sprintf_P(url, PSTR("%s/%d"), MQTT_TOPIC_RELAY, relayID);
 
         char key[10];
-        sprintf(key, "%s%d", MQTT_TOPIC_RELAY, relayID);
+        sprintf_P(key, PSTR("%s%d"), MQTT_TOPIC_RELAY, relayID);
 
         apiRegister(url, key,
             [relayID](char * buffer, size_t len) {
-				snprintf(buffer, len, "%d", relayStatus(relayID) ? 1 : 0);
+				snprintf_P(buffer, len, PSTR("%d"), relayStatus(relayID) ? 1 : 0);
             },
             [relayID](const char * payload) {
                 unsigned int value = payload[0] - '0';
@@ -362,7 +362,7 @@ void relayMQTTCallback(unsigned int type, const char * topic, const char * paylo
         #endif
 
         char buffer[strlen(MQTT_TOPIC_RELAY) + 3];
-        sprintf(buffer, "%s/+", MQTT_TOPIC_RELAY);
+        sprintf_P(buffer, PSTR("%s/+"), MQTT_TOPIC_RELAY);
         mqttSubscribe(buffer);
 
     }
@@ -412,7 +412,7 @@ void relaySetupMQTT() {
 void relayInfluxDB(unsigned char id) {
     if (id >= _relays.size()) return;
     char buffer[10];
-    sprintf(buffer, "%s,id=%d", MQTT_TOPIC_RELAY, id);
+    sprintf_P(buffer, PSTR("%s,id=%d"), MQTT_TOPIC_RELAY, id);
     influxDBSend(buffer, relayStatus(id) ? "1" : "0");
 }
 #endif
diff --git a/code/espurna/rfbridge.ino b/code/espurna/rfbridge.ino
index 4976a6af..8128e180 100644
--- a/code/espurna/rfbridge.ino
+++ b/code/espurna/rfbridge.ino
@@ -201,7 +201,7 @@ From a byte array to an hexa char array ("A220EE...", double the size)
  */
 bool _rfbToChar(byte * in, char * out) {
     for (unsigned char p = 0; p<RF_MESSAGE_SIZE; p++) {
-        sprintf(&out[p*2], "%02X", in[p]);
+        sprintf_P(&out[p*2], PSTR("%02X"), in[p]);
     }
     return true;
 }
@@ -210,7 +210,7 @@ void _rfbMqttCallback(unsigned int type, const char * topic, const char * payloa
 
     if (type == MQTT_CONNECT_EVENT) {
         char buffer[strlen(MQTT_TOPIC_RFLEARN) + 3];
-        sprintf(buffer, "%s/+", MQTT_TOPIC_RFLEARN);
+        sprintf_P(buffer, PSTR("%s/+"), MQTT_TOPIC_RFLEARN);
         mqttSubscribe(buffer);
         mqttSubscribe(MQTT_TOPIC_RFOUT);
     }
@@ -251,13 +251,13 @@ void _rfbMqttCallback(unsigned int type, const char * topic, const char * payloa
 void rfbStore(unsigned char id, bool status, const char * code) {
     DEBUG_MSG_P(PSTR("[RFBRIDGE] Storing %d-%s => '%s'\n"), id, status ? "ON" : "OFF", code);
     char key[8] = {0};
-    sprintf(key, "rfb%d%s", id, status ? "on" : "off");
+    sprintf_P(key, PSTR("rfb%d%s"), id, status ? "on" : "off");
     setSetting(key, code);
 }
 
 String rfbRetrieve(unsigned char id, bool status) {
     char key[8] = {0};
-    sprintf(key, "rfb%d%s", id, status ? "on" : "off");
+    sprintf_P(key, PSTR("rfb%d%s"), id, status ? "on" : "off");
     return getSetting(key);
 }
 
@@ -282,7 +282,7 @@ void rfbLearn(unsigned char id, bool status) {
 void rfbForget(unsigned char id, bool status) {
 
     char key[8] = {0};
-    sprintf(key, "rfb%d%s", id, status ? "on" : "off");
+    sprintf_P(key, PSTR("rfb%d%s"), id, status ? "on" : "off");
     delSetting(key);
 
     // Websocket update
diff --git a/code/espurna/web.ino b/code/espurna/web.ino
index e42cd27d..32d49b5f 100644
--- a/code/espurna/web.ino
+++ b/code/espurna/web.ino
@@ -430,7 +430,7 @@ void _wsParse(uint32_t client_id, uint8_t * payload, size_t length) {
 void _wsStart(uint32_t client_id) {
 
     char chipid[6];
-    sprintf(chipid, "%06X", ESP.getChipId());
+    sprintf_P(chipid, PSTR("%06X"), ESP.getChipId());
 
     DynamicJsonBuffer jsonBuffer;
     JsonObject& root = jsonBuffer.createObject();
@@ -776,7 +776,7 @@ ArRequestHandlerFunction _bindAPI(unsigned int apiID) {
         char *p = ltrim(value);
 
         // The response will be a 404 NOT FOUND if the resource is not available
-        if (*value == NULL) {
+        if (!value) {
             DEBUG_MSG_P(PSTR("[API] Sending 404 response\n"));
             request->send(404);
             return;
@@ -801,7 +801,7 @@ void apiRegister(const char * url, const char * key, apiGetCallbackFunction getF
     // Store it
     web_api_t api;
     char buffer[40];
-    snprintf(buffer, 39, "/api/%s", url);
+    snprintf_P(buffer, 39, PSTR("/api/%s"), url);
     api.url = strdup(buffer);
     api.key = strdup(key);
     api.getFn = getFn;
@@ -913,7 +913,7 @@ void _onGetConfig(AsyncWebServerRequest *request) {
     }
 
     char buffer[100];
-    sprintf(buffer, "attachment; filename=\"%s-backup.json\"", (char *) getSetting("hostname").c_str());
+    sprintf_P(buffer, PSTR("attachment; filename=\"%s-backup.json\""), (char *) getSetting("hostname").c_str());
     response->addHeader("Content-Disposition", buffer);
     response->setLength();
     request->send(response);
@@ -993,7 +993,7 @@ void webSetup() {
     mqttRegister(wsMQTTCallback);
 
     // Cache the Last-Modifier header value
-    sprintf(_last_modified, "%s %s GMT", __DATE__, __TIME__);
+    sprintf_P(_last_modified, PSTR("%s %s GMT"), __DATE__, __TIME__);
 
     // Setup webserver
     _server->addHandler(&ws);