diff --git a/src/protocols/RTTY/RTTY.cpp b/src/protocols/RTTY/RTTY.cpp
index 7b023f8e..ccd166cf 100644
--- a/src/protocols/RTTY/RTTY.cpp
+++ b/src/protocols/RTTY/RTTY.cpp
@@ -235,7 +235,7 @@ size_t RTTYClient::print(__FlashStringHelper* fstr) {
 
   size_t n = 0;
   if(_encoding == ITA2) {
-    ITA2String ita2 = str;
+    ITA2String ita2 = ITA2String(str);
     n = RTTYClient::print(ita2);
   } else if((_encoding == ASCII) || (_encoding == ASCII_EXTENDED)) {
     n = RTTYClient::write((uint8_t*)str, len);
@@ -256,7 +256,7 @@ size_t RTTYClient::print(ITA2String& ita2) {
 size_t RTTYClient::print(const String& str) {
   size_t n = 0;
   if(_encoding == ITA2) {
-    ITA2String ita2 = str.c_str();
+    ITA2String ita2 = ITA2String(str.c_str());
     n = RTTYClient::print(ita2);
   } else if((_encoding == ASCII) || (_encoding == ASCII_EXTENDED)) {
     n = RTTYClient::write((uint8_t*)str.c_str(), str.length());
@@ -267,7 +267,7 @@ size_t RTTYClient::print(const String& str) {
 size_t RTTYClient::print(const char str[]) {
   size_t n = 0;
   if(_encoding == ITA2) {
-    ITA2String ita2 = str;
+    ITA2String ita2 = ITA2String(str);
     n = RTTYClient::print(ita2);
   } else if((_encoding == ASCII) || (_encoding == ASCII_EXTENDED)) {
     n = RTTYClient::write((uint8_t*)str, strlen(str));
@@ -278,7 +278,7 @@ size_t RTTYClient::print(const char str[]) {
 size_t RTTYClient::print(char c) {
   size_t n = 0;
   if(_encoding == ITA2) {
-    ITA2String ita2 = c;
+    ITA2String ita2 = ITA2String(c);
     n = RTTYClient::print(ita2);
   } else if((_encoding == ASCII) || (_encoding == ASCII_EXTENDED)) {
     n = RTTYClient::write(c);
@@ -328,7 +328,7 @@ size_t RTTYClient::print(double n, int digits) {
 size_t RTTYClient::println(void) {
   size_t n = 0;
   if(_encoding == ITA2) {
-    ITA2String lf = "\r\n";
+    ITA2String lf = ITA2String("\r\n");
     n = RTTYClient::print(lf);
   } else if((_encoding == ASCII) || (_encoding == ASCII_EXTENDED)) {
     n = RTTYClient::write("\r\n");
@@ -437,7 +437,7 @@ size_t RTTYClient::printNumber(unsigned long n, uint8_t base) {
 
   size_t l = 0;
   if(_encoding == ITA2) {
-    ITA2String ita2 = str;
+    ITA2String ita2 = ITA2String(str);
     uint8_t* arr = ita2.byteArr();
     l = RTTYClient::write(arr, ita2.length());
     delete[] arr;
@@ -461,7 +461,7 @@ size_t RTTYClient::printFloat(double number, uint8_t digits)  {
 
   if(code[0] != 0x00) {
     if(_encoding == ITA2) {
-      ITA2String ita2 = code;
+      ITA2String ita2 = ITA2String(code);
       uint8_t* arr = ita2.byteArr();
       n = RTTYClient::write(arr, ita2.length());
       delete[] arr;
@@ -474,7 +474,7 @@ size_t RTTYClient::printFloat(double number, uint8_t digits)  {
   // Handle negative numbers
   if (number < 0.0) {
     if(_encoding == ITA2) {
-      ITA2String ita2 = "-";
+      ITA2String ita2 = ITA2String("-");
       uint8_t* arr = ita2.byteArr();
       n += RTTYClient::write(arr, ita2.length());
       delete[] arr;
@@ -499,7 +499,7 @@ size_t RTTYClient::printFloat(double number, uint8_t digits)  {
   // Print the decimal point, but only if there are digits beyond
   if(digits > 0) {
     if(_encoding == ITA2) {
-      ITA2String ita2 = ".";
+      ITA2String ita2 = ITA2String(".");
       uint8_t* arr = ita2.byteArr();
       n += RTTYClient::write(arr, ita2.length());
       delete[] arr;
diff --git a/src/protocols/RTTY/RTTY.h b/src/protocols/RTTY/RTTY.h
index 7dc54076..a7bfbf73 100644
--- a/src/protocols/RTTY/RTTY.h
+++ b/src/protocols/RTTY/RTTY.h
@@ -29,14 +29,14 @@ class ITA2String {
 
       \param c ASCII-encoded character to encode as ITA2.
     */
-    ITA2String(char c);
+    explicit ITA2String(char c);
 
     /*!
       \brief Default string constructor.
 
       \param str ASCII-encoded string to encode as ITA2.
     */
-    ITA2String(const char* str);
+    explicit ITA2String(const char* str);
 
     /*!
       \brief Default destructor.
@@ -69,7 +69,7 @@ class ITA2String {
     size_t _len;
     size_t _ita2Len;
 
-    uint16_t getBits(char c);
+    static uint16_t getBits(char c);
 };
 
 // supported encoding schemes
@@ -89,7 +89,7 @@ class RTTYClient {
 
       \param phy Pointer to the wireless module providing PhysicalLayer communication.
     */
-    RTTYClient(PhysicalLayer* phy);
+    explicit RTTYClient(PhysicalLayer* phy);
 
     #if !defined(RADIOLIB_EXCLUDE_AFSK)
     /*!
@@ -97,7 +97,7 @@ class RTTYClient {
 
       \param audio Pointer to the AFSK instance providing audio.
     */
-    RTTYClient(AFSKClient* audio);
+    explicit RTTYClient(AFSKClient* audio);
     #endif
 
     // basic methods
@@ -143,7 +143,7 @@ class RTTYClient {
     size_t println(void);
     size_t println(__FlashStringHelper*);
     size_t println(ITA2String &);
-    size_t println(const String &s);
+    size_t println(const String &);
     size_t println(const char[]);
     size_t println(char);
     size_t println(unsigned char, int = DEC);
@@ -163,12 +163,12 @@ class RTTYClient {
     void* _audio;
     #endif
 
-    uint8_t _encoding;
-    uint32_t _base, _baseHz;
-    uint32_t _shift, _shiftHz;
-    uint32_t _bitDuration;
-    uint8_t _dataBits;
-    uint8_t _stopBits;
+    uint8_t _encoding = ASCII;
+    uint32_t _base = 0, _baseHz = 0;
+    uint32_t _shift = 0, _shiftHz = 0;
+    uint32_t _bitDuration = 0;
+    uint8_t _dataBits = 0;
+    uint8_t _stopBits = 0;
 
     void mark();
     void space();