diff --git a/ChangeLog b/ChangeLog
index 2ea4f1a9ab..4ce8eb9948 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,28 @@
 2015-06-17  Joseph Myers  <joseph@codesourcery.com>
 
+	[BZ #18547]
+	* misc/getttyent.c (getttynam): Rename to __getttynam and define
+	as weak alias of __getttynam.  Use prototype function definition.
+	Call __setttyent, __getttyent and __endttyent instead of
+	setttyent, getttyent and endttyent.
+	(getttyent): Rename to __getttyent and define as weak alias of
+	__getttyent.  Call __setttyent instead of setttyent.  Call
+	__fgets_unlocked instead of fgets_unlocked.
+	(setttyent): Rename to __setttyent and define as weak alias of
+	__setttyent.
+	(endttyent): Rename to __endttyent and define as weak alias of
+	__endttyent.
+	* include/ttyent.h (__getttyent): Declare.  Use libc_hidden_proto.
+	(__setttyent): Likewise.
+	(__endttyent): Likewise.
+	(getttyent): Don't use libc_hidden_proto.
+	(setttyent): Likewise.
+	(endttyent): Likewise.
+	* misc/ttyslot.c (ttyslot): Call __setttyent, __getttyent and
+	__endttyent instead of setttyent, getttyent and endttyent.
+	* conform/Makefile (test-xfail-XPG4/unistd.h/linknamespace):
+	Remove variable.
+
 	[BZ #18546]
 	* socket/recv.c (__recv): Use libc_hidden_def.
 	* socket/socket.c (__socket): Likewise.
diff --git a/NEWS b/NEWS
index 1892800136..3adec9b817 100644
--- a/NEWS
+++ b/NEWS
@@ -22,7 +22,7 @@ Version 2.22
   18324, 18333, 18346, 18397, 18409, 18410, 18412, 18418, 18422, 18434,
   18444, 18468, 18469, 18470, 18479, 18483, 18495, 18496, 18497, 18498,
   18507, 18512, 18519, 18520, 18522, 18527, 18528, 18529, 18530, 18532,
-  18533, 18534, 18536, 18539, 18540, 18542, 18544, 18545, 18546.
+  18533, 18534, 18536, 18539, 18540, 18542, 18544, 18545, 18546, 18547.
 
 * Cache information can be queried via sysconf() function on s390 e.g. with
   _SC_LEVEL1_ICACHE_SIZE as argument.
diff --git a/conform/Makefile b/conform/Makefile
index 52df51ec4b..ad9cc697b4 100644
--- a/conform/Makefile
+++ b/conform/Makefile
@@ -345,4 +345,3 @@ test-xfail-XOPEN2K8/ndbm.h/linknamespace = yes
 
 # Unsorted expected failures.
 test-xfail-XPG3/unistd.h/linknamespace = yes
-test-xfail-XPG4/unistd.h/linknamespace = yes
diff --git a/include/ttyent.h b/include/ttyent.h
index e510df8260..81e52116e5 100644
--- a/include/ttyent.h
+++ b/include/ttyent.h
@@ -1,8 +1,11 @@
 #ifndef	_TTYENT_H
 # include <misc/ttyent.h>
 
-libc_hidden_proto (getttyent)
-libc_hidden_proto (setttyent)
-libc_hidden_proto (endttyent)
+extern __typeof (getttyent) __getttyent __THROW;
+libc_hidden_proto (__getttyent)
+extern __typeof (setttyent) __setttyent __THROW;
+libc_hidden_proto (__setttyent)
+extern __typeof (endttyent) __endttyent __THROW;
+libc_hidden_proto (__endttyent)
 
 #endif
diff --git a/misc/getttyent.c b/misc/getttyent.c
index 864f65f523..fcdbc2274c 100644
--- a/misc/getttyent.c
+++ b/misc/getttyent.c
@@ -44,24 +44,24 @@ static char zapchar;
 static FILE *tf;
 
 struct ttyent *
-getttynam(tty)
-	const char *tty;
+__getttynam (const char *tty)
 {
 	struct ttyent *t;
 
-	setttyent();
-	while ((t = getttyent()))
+	__setttyent();
+	while ((t = __getttyent()))
 		if (!strcmp(tty, t->ty_name))
 			break;
-	endttyent();
+	__endttyent();
 	return (t);
 }
+weak_alias (__getttynam, getttynam)
 
 static char *skip (char *) __THROW internal_function;
 static char *value (char *) __THROW internal_function;
 
 struct ttyent *
-getttyent (void)
+__getttyent (void)
 {
 	static struct ttyent tty;
 	int c;
@@ -69,11 +69,11 @@ getttyent (void)
 #define	MAXLINELENGTH	100
 	static char line[MAXLINELENGTH];
 
-	if (!tf && !setttyent())
+	if (!tf && !__setttyent())
 		return (NULL);
 	flockfile (tf);
 	for (;;) {
-		if (!fgets_unlocked(p = line, sizeof(line), tf)) {
+		if (!__fgets_unlocked(p = line, sizeof(line), tf)) {
 			funlockfile (tf);
 			return (NULL);
 		}
@@ -131,7 +131,8 @@ getttyent (void)
 		*p = '\0';
 	return (&tty);
 }
-libc_hidden_def (getttyent)
+libc_hidden_def (__getttyent)
+weak_alias (__getttyent, getttyent)
 
 #define	QUOTED	1
 
@@ -184,7 +185,7 @@ value(p)
 }
 
 int
-setttyent (void)
+__setttyent (void)
 {
 
 	if (tf) {
@@ -197,10 +198,11 @@ setttyent (void)
 	}
 	return (0);
 }
-libc_hidden_def (setttyent)
+libc_hidden_def (__setttyent)
+weak_alias (__setttyent, setttyent)
 
 int
-endttyent (void)
+__endttyent (void)
 {
 	int rval;
 
@@ -211,4 +213,5 @@ endttyent (void)
 	}
 	return (1);
 }
-libc_hidden_def (endttyent)
+libc_hidden_def (__endttyent)
+weak_alias (__endttyent, endttyent)
diff --git a/misc/ttyslot.c b/misc/ttyslot.c
index 9c69589dae..0ed14d73ea 100644
--- a/misc/ttyslot.c
+++ b/misc/ttyslot.c
@@ -53,20 +53,20 @@ ttyslot (void)
 
 	name = __alloca (buflen);
 
-	setttyent();
+	__setttyent();
 	for (cnt = 0; cnt < 3; ++cnt)
 		if (__ttyname_r (cnt, name, buflen) == 0) {
 			if ((p = rindex(name, '/')))
 				++p;
 			else
 				p = name;
-			for (slot = 1; (ttyp = getttyent()); ++slot)
+			for (slot = 1; (ttyp = __getttyent()); ++slot)
 				if (!strcmp(ttyp->ty_name, p)) {
-					endttyent();
+					__endttyent();
 					return(slot);
 				}
 			break;
 		}
-	endttyent();
+	__endttyent();
 	return(0);
 }