diff --git a/lib/screen.S b/lib/screen.S
index a3a88c5c..3aacdf3b 100644
--- a/lib/screen.S
+++ b/lib/screen.S
@@ -48,7 +48,7 @@ zproc screen_putchar, .text.screen_putchar
     jmp _call_screen
 zendproc
 
-zproc screen_putstring, .text.screen_putstring
+zproc _screen_putstring, .text.screen_putstring
     ldy #SCREEN_PUTSTRING
     jmp _call_screen
 zendproc
diff --git a/lib/screen.h b/lib/screen.h
index eec24937..6ec331dc 100644
--- a/lib/screen.h
+++ b/lib/screen.h
@@ -14,6 +14,7 @@ extern void _screen_setcursor(uint16_t c);
 extern uint16_t _screen_getcursor(void);
 extern void screen_putchar(char c);
 extern void screen_putstring(const char* s);
+extern void _screen_putstring(uint16_t s);
 extern uint16_t screen_getchar(uint16_t timeout_cs);
 extern uint8_t screen_waitchar(void);
 extern void screen_scrollup(void);
@@ -22,6 +23,9 @@ extern void screen_clear_to_eol(void);
 extern void screen_setstyle(uint8_t style);
 extern void screen_showcursor(uint8_t show);
 
+#define screen_putstring(x) \
+	_screen_putstring((uint16_t)x)
+
 #define screen_setcursor(x, y) \
 	_screen_setcursor((x) | ((y)<<8))