diff --git a/esp3d/src/modules/bluetooth/BT_service.cpp b/esp3d/src/modules/bluetooth/BT_service.cpp
index 864a3693..e8e222c6 100644
--- a/esp3d/src/modules/bluetooth/BT_service.cpp
+++ b/esp3d/src/modules/bluetooth/BT_service.cpp
@@ -214,7 +214,7 @@ void BTService::push2buffer(uint8_t * sbuf, size_t len)
     for (size_t i = 0; i < len; i++) {
         _lastflush = millis();
         //command is defined
-        if ((char(sbuf[i]) == '\n')  || (char(sbuf[i]) == '\r') ) {
+        if ((char(sbuf[i]) == '\n') || (char(sbuf[i]) == '\r')) {
             if (_buffer_size < ESP3D_BT_BUFFER_SIZE) {
                 _buffer[_buffer_size] = sbuf[i];
                 _buffer_size++;
diff --git a/esp3d/src/modules/serial/serial_service.cpp b/esp3d/src/modules/serial/serial_service.cpp
index 0fea56c2..f58432dc 100644
--- a/esp3d/src/modules/serial/serial_service.cpp
+++ b/esp3d/src/modules/serial/serial_service.cpp
@@ -204,7 +204,7 @@ void SerialService::push2buffer(uint8_t * sbuf, size_t len)
     for (size_t i = 0; i < len; i++) {
         _lastflush = millis();
         //command is defined
-        if ((char(sbuf[i]) == '\n')|| char(sbuf[i]) == '\r')) {
+        if ((char(sbuf[i]) == '\n')|| (char(sbuf[i]) == '\r')) {
             if (_buffer_size < ESP3D_SERIAL_BUFFER_SIZE) {
                 _buffer[_buffer_size] = sbuf[i];
                 _buffer_size++;
diff --git a/esp3d/src/modules/telnet/telnet_server.cpp b/esp3d/src/modules/telnet/telnet_server.cpp
index 7d022328..f159e519 100644
--- a/esp3d/src/modules/telnet/telnet_server.cpp
+++ b/esp3d/src/modules/telnet/telnet_server.cpp
@@ -212,7 +212,7 @@ void Telnet_Server::push2buffer(uint8_t * sbuf, size_t len)
                 _buffer_size++;
             }
             flushbuffer();
-        } else if (isPrintable (char(sbuf[i]) ) {
+        } else if (isPrintable (char(sbuf[i]) )) {
         if (_buffer_size < ESP3D_TELNET_BUFFER_SIZE) {
                 _buffer[_buffer_size] = sbuf[i];
                 _buffer_size++;
@@ -242,7 +242,7 @@ size_t Telnet_Server::write(uint8_t c)
 size_t Telnet_Server::write(const uint8_t *buffer, size_t size)
 {
     if (isConnected() && (size>0)) {
-        if (availableForWrite() >= size) {
+        if ((size_t)availableForWrite() >= size) {
             //push data to connected telnet client
             return _telnetClients.write(buffer, size);
         } else {