diff --git a/Nextion.cpp b/Nextion.cpp
index 587d6a3..d0495ba 100644
--- a/Nextion.cpp
+++ b/Nextion.cpp
@@ -758,6 +758,6 @@ void CNextion::sendCommand(const char* command)
 {
 	assert(command != NULL);
 
-	m_serial->write((unsigned char*)command, ::strlen(command));
+	m_serial->write((unsigned char*)command, (unsigned int)::strlen(command));
 	m_serial->write((unsigned char*)"\xFF\xFF\xFF", 3U);
 }
diff --git a/TFTSerial.cpp b/TFTSerial.cpp
index b039915..a0f7c44 100644
--- a/TFTSerial.cpp
+++ b/TFTSerial.cpp
@@ -480,7 +480,7 @@ void CTFTSerial::displayBitmap(unsigned char x, unsigned char y, const char* fil
 	m_serial->write((unsigned char*)"\x1B\x0D", 2U);
 	m_serial->write(&x, 1U);
 	m_serial->write(&y, 1U);
-	m_serial->write((unsigned char*)filename, ::strlen(filename));
+	m_serial->write((unsigned char*)filename, (unsigned int)::strlen(filename));
 	m_serial->write((unsigned char*)"\xFF", 1U);
 }
 
@@ -497,5 +497,5 @@ void CTFTSerial::displayText(const char* text)
 {
 	assert(text != NULL);
 
-	m_serial->write((unsigned char*)text, ::strlen(text));
+	m_serial->write((unsigned char*)text, (unsigned int)::strlen(text));
 }