diff --git a/HD44780.cpp b/HD44780.cpp
index 07bbf87..dcd55dd 100644
--- a/HD44780.cpp
+++ b/HD44780.cpp
@@ -28,7 +28,7 @@
 
 const char* LISTENING = "Listening                               ";
 
-CHD44780::CHD44780(unsigned int rows, unsigned int cols, const char* callsign, unsigned int dmrid, const std::vector<unsigned int>& pins) :
+CHD44780::CHD44780(unsigned int rows, unsigned int cols, const std::string& callsign, unsigned int dmrid, const std::vector<unsigned int>& pins) :
 m_rows(rows),
 m_cols(cols),
 m_callsign(callsign),
@@ -44,7 +44,7 @@ m_dmr(false)
 {
 	assert(rows > 1U);
 	assert(cols > 15U);
-	assert(callsign != NULL);
+	assert(callsign.c_str() != NULL);
 }
 
 CHD44780::~CHD44780()
@@ -93,7 +93,7 @@ void CHD44780::setIdle()
 	::lcdClear(m_fd);
 
 	::lcdPosition(m_fd, 0, 0);
-	::lcdPrintf(m_fd, "%-6s / %u", m_callsign, m_dmrid);
+	::lcdPrintf(m_fd, "%-6s / %u", m_callsign.c_str(), m_dmrid);
 
 	::lcdPosition(m_fd, 0, 1);
 	::lcdPuts(m_fd, "MMDVM Idle");
diff --git a/HD44780.h b/HD44780.h
index acce49b..1815088 100644
--- a/HD44780.h
+++ b/HD44780.h
@@ -37,7 +37,7 @@
 class CHD44780 : public IDisplay
 {
 public:
-  CHD44780(unsigned int rows, unsigned int cols, const char* callsign, unsigned int dmrid, const std::vector<unsigned int>& pins);
+  CHD44780(unsigned int rows, unsigned int cols, const std::string& callsign, unsigned int dmrid, const std::vector<unsigned int>& pins);
   virtual ~CHD44780();
 
   virtual bool open();
@@ -61,7 +61,7 @@ public:
 private:
 	unsigned int m_rows;
 	unsigned int m_cols;
-	const char*  m_callsign;
+	std::string  m_callsign;
 	unsigned int m_dmrid;
 	unsigned int m_rb;
 	unsigned int m_strb;
diff --git a/MMDVMHost.cpp b/MMDVMHost.cpp
index 7d97f54..c93c1eb 100644
--- a/MMDVMHost.cpp
+++ b/MMDVMHost.cpp
@@ -582,7 +582,7 @@ void CMMDVMHost::createDisplay()
 		LogInfo("    Port: %s", port.c_str());
 		LogInfo("    Brightness: %u", brightness);
 
-		m_display = new CTFTSerial(callsign.c_str(), dmrid, port, brightness);
+		m_display = new CTFTSerial(callsign, dmrid, port, brightness);
 	} else if (type == "Nextion") {
 		std::string port        = m_conf.getNextionPort();
 		unsigned int brightness = m_conf.getNextionBrightness();
@@ -602,7 +602,7 @@ void CMMDVMHost::createDisplay()
 			LogInfo("    Columns: %u", columns);
 			LogInfo("    Pins: %u,%u,%u,%u,%u,%u", pins.at(0U), pins.at(1U), pins.at(2U), pins.at(3U), pins.at(4U), pins.at(5U));
 
-			m_display = new CHD44780(rows, columns, callsign.c_str(), dmrid, pins);
+			m_display = new CHD44780(rows, columns, callsign, dmrid, pins);
 		}
 #endif
 	} else {
diff --git a/TFTSerial.cpp b/TFTSerial.cpp
index b6e608e..055a3df 100644
--- a/TFTSerial.cpp
+++ b/TFTSerial.cpp
@@ -44,14 +44,14 @@ const unsigned char FONT_LARGE  = 3U;
 // x = 0 to 159, y = 0 to 127 - Landscape
 // x = 0 to 127, y = 0 to 159 - Portrait
 
-CTFTSerial::CTFTSerial(const char* callsign, unsigned int dmrid, const std::string& port, unsigned int brightness) :
+CTFTSerial::CTFTSerial(const std::string& callsign, unsigned int dmrid, const std::string& port, unsigned int brightness) :
 m_callsign(callsign),
 m_dmrid(dmrid),
 m_serial(port, SERIAL_9600),
 m_brightness(brightness),
 m_mode(MODE_IDLE)
 {
-	assert(callsign != NULL);
+	assert(callsign.c_str() != NULL);
 	assert(brightness >= 0U && brightness <= 100U);
 }
 
@@ -91,7 +91,7 @@ void CTFTSerial::setIdle()
 	displayBitmap(0U, 0U, "MMDVM_sm.bmp");
 
 	char text[30];
-	::sprintf(text, "%-6s / %u", m_callsign, m_dmrid);
+	::sprintf(text, "%-6s / %u", m_callsign.c_str(), m_dmrid);
 
 	gotoPosPixel(18U, 55U);
 	displayText(text);
diff --git a/TFTSerial.h b/TFTSerial.h
index 53f6479..cbc5fad 100644
--- a/TFTSerial.h
+++ b/TFTSerial.h
@@ -28,7 +28,7 @@
 class CTFTSerial : public IDisplay
 {
 public:
-  CTFTSerial(const char* callsign, unsigned int dmrid, const std::string& port, unsigned int brightness);
+  CTFTSerial(const std::string& callsign, unsigned int dmrid, const std::string& port, unsigned int brightness);
   virtual ~CTFTSerial();
 
   virtual bool open();
@@ -50,7 +50,7 @@ public:
   virtual void close();
 
 private:
-   const char*       m_callsign;
+   std::string       m_callsign;
    unsigned int      m_dmrid;
    CSerialController m_serial;
    unsigned int      m_brightness;