diff --git a/src/stdio/vfwprintf.c b/src/stdio/vfwprintf.c
index 53697701..a653e233 100644
--- a/src/stdio/vfwprintf.c
+++ b/src/stdio/vfwprintf.c
@@ -271,7 +271,7 @@ static int wprintf_core(FILE *f, const wchar_t *fmt, va_list *ap, union arg *nl_
 		case 'C':
 			if (w<1) w=1;
 			pad(f, w-1, fl);
-			out(f, &(wchar_t){t=='C' ? arg.i : btowc(arg.i)}, 1);
+			out(f, &(wchar_t){t=='C' ? arg.i : btowc(arg.i & 0xff)}, 1);
 			pad(f, w-1, fl^LEFT_ADJ);
 			l = w;
 			continue;