1 files changed, 9 insertions, 0 deletions
diff --git a/src/multibyte/wcrtomb.c b/src/multibyte/wcrtomb.c
index 59f733db..ddc37a57 100644
--- a/src/multibyte/wcrtomb.c
+++ b/src/multibyte/wcrtomb.c
@@ -4,8 +4,10 @@
  * unnecessary.
  */
 
+#include <stdlib.h>
 #include <wchar.h>
 #include <errno.h>
+#include "internal.h"
 
 size_t wcrtomb(char *restrict s, wchar_t wc, mbstate_t *restrict st)
 {
@@ -13,6 +15,13 @@ size_t wcrtomb(char *restrict s, wchar_t wc, mbstate_t *restrict st)
 	if ((unsigned)wc < 0x80) {
 		*s = wc;
 		return 1;
+	} else if (MB_CUR_MAX == 1) {
+		if (!IS_CODEUNIT(wc)) {
+			errno = EILSEQ;
+			return -1;
+		}
+		*s = wc;
+		return 1;
 	} else if ((unsigned)wc < 0x800) {
 		*s++ = 0xc0 | (wc>>6);
 		*s = 0x80 | (wc&0x3f);