diff --git a/src/internal/libc.h b/src/internal/libc.h
index 212f0e8bd8ff8263aad8821bc87420a965b0b0cd..6810cd8b97f40b7a8f7bae0a9086eb5096022395 100644
--- a/src/internal/libc.h
+++ b/src/internal/libc.h
@@ -8,9 +8,7 @@
 struct __locale_map;
 
 struct __locale_struct {
-	volatile int ctype_utf8;
-	char *messages_name;
-	struct __locale_map *volatile cat[4];
+	const struct __locale_map *volatile cat[6];
 };
 
 struct __libc {
diff --git a/src/internal/locale_impl.h b/src/internal/locale_impl.h
index 5aebbf68866a8241e0c6aa4c3b4498496c30d1cb..9b8385e96aaa32da6763f93b7cb78ffe691b72fa 100644
--- a/src/internal/locale_impl.h
+++ b/src/internal/locale_impl.h
@@ -9,20 +9,20 @@ struct __locale_map {
 	const void *map;
 	size_t map_size;
 	char name[LOCALE_NAME_MAX+1];
-	struct __locale_map *next;
+	const struct __locale_map *next;
 };
 
-int __setlocalecat(locale_t, int, const char *);
+const struct __locale_map *__get_locale(int, const char *);
 const char *__mo_lookup(const void *, size_t, const char *);
 const char *__lctrans(const char *, const struct __locale_map *);
 const char *__lctrans_cur(const char *);
 
-#define LCTRANS(msg, lc, loc) __lctrans(msg, (loc)->cat[(lc)-2])
+#define LCTRANS(msg, lc, loc) __lctrans(msg, (loc)->cat[(lc)])
 #define LCTRANS_CUR(msg) __lctrans_cur(msg)
 
 #define CURRENT_LOCALE (__pthread_self()->locale)
 
-#define CURRENT_UTF8 (__pthread_self()->locale->ctype_utf8)
+#define CURRENT_UTF8 (!!__pthread_self()->locale->cat[LC_CTYPE])
 
 #undef MB_CUR_MAX
 #define MB_CUR_MAX (CURRENT_UTF8 ? 4 : 1)
diff --git a/src/locale/__lctrans.c b/src/locale/__lctrans.c
index 15994c570a50b26c14a574876a69f22d0d0ecce1..107fe14a3a36d64176c611cf09c3aedb25fbc3b7 100644
--- a/src/locale/__lctrans.c
+++ b/src/locale/__lctrans.c
@@ -16,5 +16,5 @@ const char *__lctrans(const char *msg, const struct __locale_map *lm)
 
 const char *__lctrans_cur(const char *msg)
 {
-	return __lctrans_impl(msg, CURRENT_LOCALE->cat[LC_MESSAGES-2]);
+	return __lctrans_impl(msg, CURRENT_LOCALE->cat[LC_MESSAGES]);
 }
diff --git a/src/locale/__setlocalecat.c b/src/locale/__setlocalecat.c
index e829da56759b5ae7f42132abb6d48e37c9d97dfc..30aa7fcc3d9595285d05ae37c795243882bddcf4 100644
--- a/src/locale/__setlocalecat.c
+++ b/src/locale/__setlocalecat.c
@@ -15,24 +15,60 @@ const unsigned char *__map_file(const char *, size_t *);
 int __munmap(void *, size_t);
 char *__strchrnul(const char *, int);
 
-static struct __locale_map *findlocale(const char *name, size_t n)
+static const char envvars[][12] = {
+	"LC_CTYPE",
+	"LC_NUMERIC",
+	"LC_TIME",
+	"LC_COLLATE",
+	"LC_MONETARY",
+	"LC_MESSAGES",
+};
+
+static const uint32_t empty_mo[] = { 0x950412de, 0, -1, -1, -1 };
+
+static const struct __locale_map c_dot_utf8 = {
+	.map = empty_mo,
+	.map_size = sizeof empty_mo,
+	.name = "C.UTF-8"
+};
+
+const struct __locale_map *__get_locale(int cat, const char *val)
 {
 	static int lock[2];
 	static void *volatile loc_head;
-	struct __locale_map *p, *new = 0;
+	const struct __locale_map *p;
+	struct __locale_map *new = 0;
 	const char *path = 0, *z;
 	char buf[256];
-	size_t l;
-	const void *map;
-	size_t map_size;
+	size_t l, n;
+
+	if (!*val) {
+		(val = getenv("LC_ALL")) && *val ||
+		(val = getenv(envvars[cat])) && *val ||
+		(val = getenv("LANG")) && *val ||
+		(val = "C.UTF-8");
+	}
+
+	/* Limit name length and forbid leading dot or any slashes. */
+	for (n=0; n<LOCALE_NAME_MAX && val[n] && val[n]!='/'; n++);
+	if (val[0]=='.' || val[n]) val = "C.UTF-8";
+	int builtin = (val[0]=='C' && !val[1])
+		|| !strcmp(val, "C.UTF-8")
+		|| !strcmp(val, "POSIX");
+
+	if (builtin) {
+		if (cat == LC_CTYPE && val[1]=='.')
+			return (void *)&c_dot_utf8;
+		return 0;
+	}
 
 	for (p=loc_head; p; p=p->next)
-		if (!strcmp(name, p->name)) return p;
+		if (!strcmp(val, p->name)) return p;
 
 	LOCK(lock);
 
 	for (p=loc_head; p; p=p->next)
-		if (!strcmp(name, p->name)) {
+		if (!strcmp(val, p->name)) {
 			UNLOCK(lock);
 			return p;
 		}
@@ -46,9 +82,10 @@ static struct __locale_map *findlocale(const char *name, size_t n)
 		if (l >= sizeof buf - n - 2) continue;
 		memcpy(buf, path, l);
 		buf[l] = '/';
-		memcpy(buf+l+1, name, n);
+		memcpy(buf+l+1, val, n);
 		buf[l+1+n] = 0;
-		map = __map_file(buf, &map_size);
+		size_t map_size;
+		const void *map = __map_file(buf, &map_size);
 		if (map) {
 			new = malloc(sizeof *new);
 			if (!new) {
@@ -57,58 +94,31 @@ static struct __locale_map *findlocale(const char *name, size_t n)
 			}
 			new->map = map;
 			new->map_size = map_size;
-			memcpy(new->name, name, n);
+			memcpy(new->name, val, n);
 			new->name[n] = 0;
 			new->next = loc_head;
 			loc_head = new;
 			break;
 		}
 	}
-	UNLOCK(lock);
-	return new;
-}
-
-static const char envvars[][12] = {
-	"LC_CTYPE",
-	"LC_NUMERIC",
-	"LC_TIME",
-	"LC_COLLATE",
-	"LC_MONETARY",
-	"LC_MESSAGES",
-};
 
-int __setlocalecat(locale_t loc, int cat, const char *val)
-{
-	if (!*val) {
-		(val = getenv("LC_ALL")) && *val ||
-		(val = getenv(envvars[cat])) && *val ||
-		(val = getenv("LANG")) && *val ||
-		(val = "C.UTF-8");
+	/* If no locale definition was found, make a locale map
+	 * object anyway to store the name, which is kept for the
+	 * sake of being able to do message translations at the
+	 * application level. */
+	if (!new && (new = malloc(sizeof *new))) {
+		new->map = empty_mo;
+		new->map_size = sizeof empty_mo;
+		memcpy(new->name, val, n);
+		new->name[n] = 0;
+		new->next = loc_head;
+		loc_head = new;
 	}
 
-	size_t n;
-	for (n=0; n<LOCALE_NAME_MAX && val[n] && val[n]!='/'; n++);
-	if (val[0]=='.' || val[n]) val = "C.UTF-8";
-	int builtin = (val[0]=='C' && !val[1])
-		|| !strcmp(val, "C.UTF-8")
-		|| !strcmp(val, "POSIX");
+	/* For LC_CTYPE, never return a null pointer unless the
+	 * requested name was "C" or "POSIX". */
+	if (!new && cat == LC_CTYPE) new = (void *)&c_dot_utf8;
 
-	switch (cat) {
-	case LC_CTYPE:
-		loc->ctype_utf8 = !builtin || val[1]=='.';
-		break;
-	case LC_MESSAGES:
-		if (builtin) {
-			loc->messages_name[0] = 0;
-		} else {
-			memcpy(loc->messages_name, val, n);
-			loc->messages_name[n] = 0;
-		}
-		/* fall through */
-	default:
-		loc->cat[cat-2] = builtin ? 0 : findlocale(val, n);
-	case LC_NUMERIC:
-		break;
-	}
-	return 0;
+	UNLOCK(lock);
+	return new;
 }
diff --git a/src/locale/dcngettext.c b/src/locale/dcngettext.c
index 30dd41d4d83c9d06b70cda9b5c4fe4c33971852e..a5ff847504f58a5904dc2a949e73a354661f3a08 100644
--- a/src/locale/dcngettext.c
+++ b/src/locale/dcngettext.c
@@ -84,13 +84,15 @@ char *bindtextdomain(const char *domainname, const char *dirname)
 }
 
 static const char catnames[][12] = {
+	"LC_CTYPE",
+	"LC_NUMERIC",
 	"LC_TIME",
 	"LC_COLLATE",
 	"LC_MONETARY",
 	"LC_MESSAGES",
 };
 
-static const char catlens[] = { 7, 10, 11, 11 };
+static const char catlens[] = { 8, 10, 7, 10, 11, 11 };
 
 struct msgcat {
 	struct msgcat *next;
@@ -117,10 +119,12 @@ char *dcngettext(const char *domainname, const char *msgid1, const char *msgid2,
 	static struct msgcat *volatile cats;
 	struct msgcat *p;
 	struct __locale_struct *loc = CURRENT_LOCALE;
-	struct __locale_map *lm;
+	const struct __locale_map *lm;
 	const char *dirname, *locname, *catname;
 	size_t dirlen, loclen, catlen, domlen;
 
+	if ((unsigned)category >= LC_ALL) goto notrans;
+
 	if (!domainname) domainname = __gettextdomain();
 
 	domlen = strlen(domainname);
@@ -129,25 +133,15 @@ char *dcngettext(const char *domainname, const char *msgid1, const char *msgid2,
 	dirname = gettextdir(domainname, &dirlen);
 	if (!dirname) goto notrans;
 
-	switch (category) {
-	case LC_MESSAGES:
-		locname = loc->messages_name;
-		if (!locname || !*locname) goto notrans;
-		break;
-	case LC_TIME:
-	case LC_MONETARY:
-	case LC_COLLATE:
-		lm = loc->cat[category-2];
-		if (!lm) goto notrans;
-		locname = lm->name;
-		break;
-	default:
+	lm = loc->cat[category];
+	if (!lm) {
 notrans:
 		return (char *) ((n == 1) ? msgid1 : msgid2);
 	}
+	locname = lm->name;
 
-	catname = catnames[category-2];
-	catlen = catlens[category-2];
+	catname = catnames[category];
+	catlen = catlens[category];
 	loclen = strlen(locname);
 
 	size_t namelen = dirlen+1 + loclen+1 + catlen+1 + domlen+3;
diff --git a/src/locale/duplocale.c b/src/locale/duplocale.c
index b87c933e4d27f30aac5169d4a682871ddeb9565e..030b64cb0e706cdf29c7104526e86b6ee08d7adb 100644
--- a/src/locale/duplocale.c
+++ b/src/locale/duplocale.c
@@ -5,17 +5,10 @@
 
 locale_t __duplocale(locale_t old)
 {
-	locale_t new = calloc(1, sizeof *new + LOCALE_NAME_MAX + 1);
+	locale_t new = malloc(sizeof *new);
 	if (!new) return 0;
-	new->messages_name = (void *)(new+1);
-
 	if (old == LC_GLOBAL_LOCALE) old = &libc.global_locale;
-	new->ctype_utf8 = old->ctype_utf8;
-	if (old->messages_name)
-		strcpy(new->messages_name, old->messages_name);
-
-	for (size_t i=0; i<sizeof new->cat/sizeof new->cat[0]; i++)
-		new->cat[i] = old->cat[i];
+	*new = *old;
 	return new;
 }
 
diff --git a/src/locale/newlocale.c b/src/locale/newlocale.c
index 39501d0c1b9a3305cbd2405e716dc06620d310c7..4e0cbd34072f23675cda75cf047dfc9fbace184d 100644
--- a/src/locale/newlocale.c
+++ b/src/locale/newlocale.c
@@ -8,17 +8,16 @@ locale_t __newlocale(int mask, const char *name, locale_t loc)
 	int i;
 
 	if (!loc) {
-		loc = calloc(1, sizeof *loc + LOCALE_NAME_MAX + 1);
+		loc = malloc(sizeof *loc);
 		if (!loc) return 0;
-		loc->messages_name = (void *)(loc+1);
 		for (i=0; i<LC_ALL; i++)
 			if (!(mask & (1<<i)))
-				__setlocalecat(loc, i, "");
+				loc->cat[i] = __get_locale(i, "");
 	}
 
 	for (i=0; i<LC_ALL; i++)
 		if (mask & (1<<i))
-			__setlocalecat(loc, i, name);
+			loc->cat[i] = __get_locale(i, name);
 
 	return loc;
 }
diff --git a/src/locale/setlocale.c b/src/locale/setlocale.c
index 32a8fcab5fde043654ed06a16820f9464bce1981..8dae5a4e8e446b9027aff4bdd5005a6b1c43142b 100644
--- a/src/locale/setlocale.c
+++ b/src/locale/setlocale.c
@@ -5,38 +5,23 @@
 #include "libc.h"
 #include "atomic.h"
 
-static char buf[2+4*(LOCALE_NAME_MAX+1)];
+static char buf[LC_ALL*(LOCALE_NAME_MAX+1)];
 
 static char *setlocale_one_unlocked(int cat, const char *name)
 {
-	struct __locale_map *lm;
+	const struct __locale_map *lm;
 
-	if (name) __setlocalecat(&libc.global_locale, cat, name);
+	if (name) libc.global_locale.cat[cat] = lm = __get_locale(cat, name);
+	else lm = libc.global_locale.cat[cat];
 
-	switch (cat) {
-	case LC_CTYPE:
-		return libc.global_locale.ctype_utf8 ? "C.UTF-8" : "C";
-	case LC_NUMERIC:
-		return "C";
-	case LC_MESSAGES:
-		return libc.global_locale.messages_name[0]
-			? libc.global_locale.messages_name : "C";
-	default:
-		lm = libc.global_locale.cat[cat-2];
-		return lm ? lm->name : "C";
-	}
+	return lm ? (char *)lm->name : "C";
 }
 
+char *__strchrnul(const char *, int);
+
 char *setlocale(int cat, const char *name)
 {
 	static volatile int lock[2];
-	struct __locale_map *lm;
-	int i, j;
-
-	if (!libc.global_locale.messages_name) {
-		libc.global_locale.messages_name =
-			buf + 2 + 3*(LOCALE_NAME_MAX+1);
-	}
 
 	if ((unsigned)cat > LC_ALL) return 0;
 
@@ -48,34 +33,31 @@ char *setlocale(int cat, const char *name)
 	 * performs both the serialization and deserialization, depends
 	 * on the format, so it can easily be changed if needed. */
 	if (cat == LC_ALL) {
+		int i;
 		if (name) {
-			char part[LOCALE_NAME_MAX+1];
-			if (name[0] && name[1]==';'
-			    && strlen(name) > 2 + 3*(LOCALE_NAME_MAX+1)) {
-				part[0] = name[0];
-				part[1] = 0;
-				setlocale(LC_CTYPE, part);
-				part[LOCALE_NAME_MAX] = 0;
-				for (i=LC_TIME; i<LC_MESSAGES; i++) {
-					memcpy(part, name + 2 + (i-2)*(LOCALE_NAME_MAX+1), LOCALE_NAME_MAX);
-					for (j=LOCALE_NAME_MAX-1; j && part[j]==';'; j--)
-						part[j] = 0;
-					setlocale_one_unlocked(i, part);
+			char part[LOCALE_NAME_MAX+1] = "C.UTF-8";
+			const char *p = name;
+			for (i=0; i<LC_ALL; i++) {
+				const char *z = __strchrnul(p, ';');
+				if (z-p <= LOCALE_NAME_MAX) {
+					memcpy(part, p, z-p);
+					part[z-p] = 0;
+					if (*z) p = z+1;
 				}
-				setlocale_one_unlocked(LC_MESSAGES, name
-					+ 2 + 3*(LOCALE_NAME_MAX+1));
-			} else {
-				for (i=0; i<LC_ALL; i++)
-					setlocale_one_unlocked(i, name);
+				setlocale_one_unlocked(i, part);
 			}
 		}
-		memset(buf, ';', 2 + 3*(LOCALE_NAME_MAX+1));
-		buf[0] = libc.global_locale.ctype_utf8 ? 'U' : 'C';
-		for (i=LC_TIME; i<LC_MESSAGES; i++) {
-			lm = libc.global_locale.cat[i-2];
-			if (lm) memcpy(buf + 2 + (i-2)*(LOCALE_NAME_MAX+1),
-				lm->name, strlen(lm->name));
+		char *s = buf;
+		for (i=0; i<LC_ALL; i++) {
+			const struct __locale_map *lm =
+				libc.global_locale.cat[i];
+			const char *part = lm ? lm->name : "C";
+			size_t l = strlen(part);
+			memcpy(s, part, l);
+			s[l] = ';';
+			s += l+1;
 		}
+		*--s = 0;
 		UNLOCK(lock);
 		return buf;
 	}