diff --git a/src/internal/stdio_impl.h b/src/internal/stdio_impl.h
index e1325fe..72c5519 100644
--- a/src/internal/stdio_impl.h
+++ b/src/internal/stdio_impl.h
@@ -47,6 +47,7 @@ struct _IO_FILE {
 	unsigned char *shend;
 	off_t shlim, shcnt;
 	FILE *prev_locked, *next_locked;
+	struct __locale_struct *locale;
 };
 
 size_t __stdio_read(FILE *, unsigned char *, size_t);
diff --git a/src/locale/iconv.c b/src/locale/iconv.c
index e6121ae..1eeea94 100644
--- a/src/locale/iconv.c
+++ b/src/locale/iconv.c
@@ -5,6 +5,7 @@
 #include <stdlib.h>
 #include <limits.h>
 #include <stdint.h>
+#include "locale_impl.h"
 
 #define UTF_32BE    0300
 #define UTF_16LE    0301
@@ -165,9 +166,12 @@ size_t iconv(iconv_t cd0, char **restrict in, size_t *restrict inb, char **restr
 	int err;
 	unsigned char type = map[-1];
 	unsigned char totype = tomap[-1];
+	locale_t *ploc = &CURRENT_LOCALE, loc = *ploc;
 
 	if (!in || !*in || !*inb) return 0;
 
+	*ploc = UTF8_LOCALE;
+
 	for (; *inb; *in+=l, *inb-=l) {
 		c = *(unsigned char *)*in;
 		l = 1;
@@ -431,6 +435,7 @@ size_t iconv(iconv_t cd0, char **restrict in, size_t *restrict inb, char **restr
 			break;
 		}
 	}
+	*ploc = loc;
 	return x;
 ilseq:
 	err = EILSEQ;
@@ -445,5 +450,6 @@ starved:
 	x = -1;
 end:
 	errno = err;
+	*ploc = loc;
 	return x;
 }
diff --git a/src/stdio/fgetwc.c b/src/stdio/fgetwc.c
index b261b44..e455cfe 100644
--- a/src/stdio/fgetwc.c
+++ b/src/stdio/fgetwc.c
@@ -1,8 +1,9 @@
 #include "stdio_impl.h"
+#include "locale_impl.h"
 #include <wchar.h>
 #include <errno.h>
 
-wint_t __fgetwc_unlocked(FILE *f)
+static wint_t __fgetwc_unlocked_internal(FILE *f)
 {
 	mbstate_t st = { 0 };
 	wchar_t wc;
@@ -10,8 +11,6 @@ wint_t __fgetwc_unlocked(FILE *f)
 	unsigned char b;
 	size_t l;
 
-	if (f->mode <= 0) fwide(f, 1);
-
 	/* Convert character from buffer if possible */
 	if (f->rpos < f->rend) {
 		l = mbrtowc(&wc, (void *)f->rpos, f->rend - f->rpos, &st);
@@ -39,6 +38,16 @@ wint_t __fgetwc_unlocked(FILE *f)
 	return wc;
 }
 
+wint_t __fgetwc_unlocked(FILE *f)
+{
+	locale_t *ploc = &CURRENT_LOCALE, loc = *ploc;
+	if (f->mode <= 0) fwide(f, 1);
+	*ploc = f->locale;
+	wchar_t wc = __fgetwc_unlocked_internal(f);
+	*ploc = loc;
+	return wc;
+}
+
 wint_t fgetwc(FILE *f)
 {
 	wint_t c;
diff --git a/src/stdio/fputwc.c b/src/stdio/fputwc.c
index 1bf165b..0be5666 100644
--- a/src/stdio/fputwc.c
+++ b/src/stdio/fputwc.c
@@ -1,4 +1,5 @@
 #include "stdio_impl.h"
+#include "locale_impl.h"
 #include <wchar.h>
 #include <limits.h>
 #include <ctype.h>
@@ -7,8 +8,10 @@ wint_t __fputwc_unlocked(wchar_t c, FILE *f)
 {
 	char mbc[MB_LEN_MAX];
 	int l;
+	locale_t *ploc = &CURRENT_LOCALE, loc = *ploc;
 
 	if (f->mode <= 0) fwide(f, 1);
+	*ploc = f->locale;
 
 	if (isascii(c)) {
 		c = putc_unlocked(c, f);
@@ -18,8 +21,11 @@ wint_t __fputwc_unlocked(wchar_t c, FILE *f)
 		else f->wpos += l;
 	} else {
 		l = wctomb(mbc, c);
-		if (l < 0 || __fwritex((void *)mbc, l, f) < l) c = WEOF;
+		if (l < 0 || __fwritex((void *)mbc, l, f) < l)
+			c = WEOF;
 	}
+	if (c==WEOF) f->flags |= F_ERR;
+	*ploc = loc;
 	return c;
 }
 
diff --git a/src/stdio/fputws.c b/src/stdio/fputws.c
index 317d65f..0ed02f1 100644
--- a/src/stdio/fputws.c
+++ b/src/stdio/fputws.c
@@ -1,23 +1,28 @@
 #include "stdio_impl.h"
+#include "locale_impl.h"
 #include <wchar.h>
 
 int fputws(const wchar_t *restrict ws, FILE *restrict f)
 {
 	unsigned char buf[BUFSIZ];
 	size_t l=0;
+	locale_t *ploc = &CURRENT_LOCALE, loc = *ploc;
 
 	FLOCK(f);
 
 	fwide(f, 1);
+	*ploc = f->locale;
 
 	while (ws && (l = wcsrtombs((void *)buf, (void*)&ws, sizeof buf, 0))+1 > 1)
 		if (__fwritex(buf, l, f) < l) {
 			FUNLOCK(f);
+			*ploc = loc;
 			return -1;
 		}
 
 	FUNLOCK(f);
 
+	*ploc = loc;
 	return l; /* 0 or -1 */
 }
 
diff --git a/src/stdio/fwide.c b/src/stdio/fwide.c
index 8088e7a..8410b15 100644
--- a/src/stdio/fwide.c
+++ b/src/stdio/fwide.c
@@ -1,13 +1,14 @@
-#include <wchar.h>
 #include "stdio_impl.h"
-
-#define SH (8*sizeof(int)-1)
-#define NORMALIZE(x) ((x)>>SH | -((-(x))>>SH))
+#include "locale_impl.h"
 
 int fwide(FILE *f, int mode)
 {
 	FLOCK(f);
-	if (!f->mode) f->mode = NORMALIZE(mode);
+	if (mode) {
+		if (!f->locale) f->locale = MB_CUR_MAX==1
+			? C_LOCALE : UTF8_LOCALE;
+		if (!f->mode) f->mode = mode>0 ? 1 : -1;
+	}
 	mode = f->mode;
 	FUNLOCK(f);
 	return mode;
diff --git a/src/stdio/ungetwc.c b/src/stdio/ungetwc.c
index d4c7de3..80d6e20 100644
--- a/src/stdio/ungetwc.c
+++ b/src/stdio/ungetwc.c
@@ -1,4 +1,5 @@
 #include "stdio_impl.h"
+#include "locale_impl.h"
 #include <wchar.h>
 #include <limits.h>
 #include <ctype.h>
@@ -8,15 +9,18 @@ wint_t ungetwc(wint_t c, FILE *f)
 {
 	unsigned char mbc[MB_LEN_MAX];
 	int l=1;
+	locale_t *ploc = &CURRENT_LOCALE, loc = *ploc;
 
 	FLOCK(f);
 
 	if (f->mode <= 0) fwide(f, 1);
+	*ploc = f->locale;
 
 	if (!f->rpos) __toread(f);
 	if (!f->rpos || f->rpos < f->buf - UNGET + l || c == WEOF ||
 	    (!isascii(c) && (l = wctomb((void *)mbc, c)) < 0)) {
 		FUNLOCK(f);
+		*ploc = loc;
 		return WEOF;
 	}
 
@@ -26,5 +30,6 @@ wint_t ungetwc(wint_t c, FILE *f)
 	f->flags &= ~F_EOF;
 
 	FUNLOCK(f);
+	*ploc = loc;
 	return c;
 }