diff --git a/libraries/FastSerial/BetterStream.cpp b/libraries/FastSerial/BetterStream.cpp
index e8cb7b97be..47519b9295 100644
--- a/libraries/FastSerial/BetterStream.cpp
+++ b/libraries/FastSerial/BetterStream.cpp
@@ -44,15 +44,21 @@ BetterStream::printf(const char *fmt, ...)
 }
 
 void
-BetterStream::_printf_P(const prog_char *fmt, ...)
+BetterStream::_printf_P(const prog_char_t *fmt, ...)
 {
         va_list ap;
 
         va_start(ap, fmt);
-        _vprintf(1, fmt, ap);
+        _vprintf(1, (const char *)fmt, ap);
         va_end(ap);
 }
 
+void
+BetterStream::vprintf_P(const prog_char_t *fmt, va_list ap)
+{
+        _vprintf(1, (const char *)fmt, ap);
+}
+
 int
 BetterStream::txspace(void)
 {
diff --git a/libraries/FastSerial/BetterStream.h b/libraries/FastSerial/BetterStream.h
index 791075ad4d..f21c3d8185 100644
--- a/libraries/FastSerial/BetterStream.h
+++ b/libraries/FastSerial/BetterStream.h
@@ -25,12 +25,13 @@ public:
         void            println_P(const prog_char_t *);
         void            printf(const char *, ...)
                 __attribute__ ((format(__printf__, 2, 3)));
-        void            _printf_P(const prog_char *, ...);
+        void            _printf_P(const prog_char_t *, ...);
                 __attribute__ ((format(__printf__, 2, 3)));
+        void            vprintf_P(const prog_char_t *, va_list);
 
         virtual int     txspace(void);
 
-#define printf_P(fmt, ...) _printf_P((const prog_char *)fmt, ## __VA_ARGS__)
+#define printf_P(fmt, ...) _printf_P((const prog_char_t *)fmt, ## __VA_ARGS__)
 
 private:
         void            _vprintf(unsigned char, const char *, va_list)