diff --git a/aircraft_gui.c b/aircraft_gui.c
--- a/aircraft_gui.c
+++ b/aircraft_gui.c
@@ -151,7 +151,7 @@ static void NewAircraftWndProc(Window *w
 		break;
 
 	case WE_ON_EDIT_TEXT: {
-		byte *b = e->edittext.str;
+		const char *b = e->edittext.str;
 		if (*b == 0)
 			return;
 		memcpy(_decode_parameters, b, 32);
@@ -506,7 +506,7 @@ change_int:
 		break;
 
 	case WE_ON_EDIT_TEXT: {
-		byte *b = e->edittext.str;
+		const char *b = e->edittext.str;
 		if (*b == 0)
 			return;
 		memcpy(_decode_parameters, b, 32);