diff --git a/lib/libc/stdio/fgetwc.c b/lib/libc/stdio/fgetwc.c
index 93438a60035c..3a6e6e135e04 100644
--- a/lib/libc/stdio/fgetwc.c
+++ b/lib/libc/stdio/fgetwc.c
@@ -78,7 +78,6 @@ static __inline wint_t
 __fgetwc_nbf(FILE *fp)
 {
 	char buf[MB_LEN_MAX];
-	mbstate_t mbs;
 	size_t n, nconv;
 	int c;
 	wchar_t wc;
@@ -91,8 +90,7 @@ __fgetwc_nbf(FILE *fp)
 			break;
 		}
 		buf[n++] = (char)c;
-		memset(&mbs, 0, sizeof(mbs));
-		nconv = mbrtowc(&wc, buf, n, &mbs);
+		nconv = mbrtowc(&wc, buf, n, NULL);
 		if (nconv == n)
 			return (wc);
 		else if (nconv == 0)
diff --git a/lib/libc/stdio/fputwc.c b/lib/libc/stdio/fputwc.c
index ed1f11bbcccb..ba3c5bbfdf82 100644
--- a/lib/libc/stdio/fputwc.c
+++ b/lib/libc/stdio/fputwc.c
@@ -44,7 +44,6 @@ wint_t
 __fputwc(wchar_t wc, FILE *fp)
 {
 	char buf[MB_LEN_MAX];
-	mbstate_t mbs;
 	size_t i, len;
 
 	if (MB_CUR_MAX == 1 && wc > 0 && wc <= UCHAR_MAX) {
@@ -56,8 +55,7 @@ __fputwc(wchar_t wc, FILE *fp)
 		*buf = (unsigned char)wc;
 		len = 1;
 	} else {
-		memset(&mbs, 0, sizeof(mbs));
-		if ((len = wcrtomb(buf, wc, &mbs)) == (size_t)-1) {
+		if ((len = wcrtomb(buf, wc, NULL)) == (size_t)-1) {
 			fp->_flags |= __SERR;
 			return (WEOF);
 		}
diff --git a/lib/libc/stdio/ungetwc.c b/lib/libc/stdio/ungetwc.c
index e20a763c47ee..c9d5c490b3c2 100644
--- a/lib/libc/stdio/ungetwc.c
+++ b/lib/libc/stdio/ungetwc.c
@@ -43,13 +43,11 @@ wint_t
 __ungetwc(wint_t wc, FILE *fp)
 {
 	char buf[MB_LEN_MAX];
-	mbstate_t mbs;
 	size_t len;
 
 	if (wc == WEOF)
 		return (WEOF);
-	memset(&mbs, 0, sizeof(mbs));
-	if ((len = wcrtomb(buf, wc, &mbs)) == (size_t)-1) {
+	if ((len = wcrtomb(buf, wc, NULL)) == (size_t)-1) {
 		fp->_flags |= __SERR;
 		return (WEOF);
 	}