diff --git a/ChangeLog b/ChangeLog
index 38825b55..d0e07da2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,15 @@
+2008-05-25  Nicolas François  <nicolas.francois@centraliens.net>
+
+	* libmisc/chkname.h, libmisc/chkname.c: check_group_name (resp.
+	check_user_name) renamed to is_valid_user_name (resp.
+	is_valid_group_name). is_valid_user_name and is_valid_group_name
+	return a bool.
+	* src/grpck.c, src/newusers.c, src/usermod.c, src/useradd.c,
+	src/groupmod.c, src/pwck.c, src/groupadd.c: Use is_valid_user_name
+	and is_valid_group_name, following above change.
+	* libmisc/chkname.c: Avoid implicit conversion of chars to
+	booleans. Add brackets and parenthesis.
+
 2008-05-25  Nicolas François  <nicolas.francois@centraliens.net>
 
 	* libmisc/xmalloc.c: Avoid implicit conversion of integers /
diff --git a/libmisc/chkname.c b/libmisc/chkname.c
index a0aa738f..2bdc06b6 100644
--- a/libmisc/chkname.c
+++ b/libmisc/chkname.c
@@ -31,8 +31,11 @@
  */
 
 /*
- * check_user_name(), check_group_name() - check the new user/group
- * name for validity; return value: 1 - OK, 0 - bad name
+ * is_valid_user_name(), is_valid_group_name() - check the new user/group
+ * name for validity;
+ * return values:
+ *   true  - OK
+ *   false - bad name
  */
 
 #include <config.h>
@@ -47,26 +50,32 @@
 #else
 #include <utmp.h>
 #endif
-static int good_name (const char *name)
+
+static bool is_valid_name (const char *name)
 {
 	/*
 	 * User/group names must match [a-z_][a-z0-9_-]*[$]
 	 */
-	if (!*name || !((*name >= 'a' && *name <= 'z') || *name == '_'))
-		return 0;
-
-	while (*++name) {
-		if (!((*name >= 'a' && *name <= 'z') ||
-		      (*name >= '0' && *name <= '9') ||
-		      *name == '_' || *name == '-' ||
-		      (*name == '$' && *(name + 1) == '\0')))
-			return 0;
+	if (('\0' == *name) ||
+	    !((('a' <= *name) && ('z' >= *name)) || ('_' == *name))) {
+		return false;
 	}
 
-	return 1;
+	while ('\0' != *++name) {
+		if (!(( ('a' <= *name) && ('z' >= *name) ) ||
+		      ( ('0' <= *name) && ('9' >= *name) ) ||
+		      ('_' == *name) ||
+		      ('-' == *name) ||
+		      ( ('$' == *name) && ('\0' == *(name + 1)) )
+		     )) {
+			return false;
+		}
+	}
+
+	return true;
 }
 
-int check_user_name (const char *name)
+bool is_valid_user_name (const char *name)
 {
 #if HAVE_UTMPX_H
 	struct utmpx ut;
@@ -78,21 +87,23 @@ int check_user_name (const char *name)
 	 * User names are limited by whatever utmp can
 	 * handle (usually max 8 characters).
 	 */
-	if (strlen (name) > sizeof (ut.ut_user))
-		return 0;
+	if (strlen (name) > sizeof (ut.ut_user)) {
+		return false;
+	}
 
-	return good_name (name);
+	return is_valid_name (name);
 }
 
-int check_group_name (const char *name)
+bool is_valid_group_name (const char *name)
 {
 	/*
 	 * Arbitrary limit for group names - max 16
 	 * characters (same as on HP-UX 10).
 	 */
-	if (strlen (name) > 16)
-		return 0;
+	if (strlen (name) > 16) {
+		return false;
+	}
 
-	return good_name (name);
+	return is_valid_name (name);
 }
 
diff --git a/libmisc/chkname.h b/libmisc/chkname.h
index 7660eefe..82c91598 100644
--- a/libmisc/chkname.h
+++ b/libmisc/chkname.h
@@ -34,13 +34,16 @@
 #define _CHKNAME_H_
 
 /*
- * check_user_name(), check_group_name() - check the new user/group
- * name for validity; return value: 1 - OK, 0 - bad name
+ * is_valid_user_name(), is_valid_group_name() - check the new user/group
+ * name for validity;
+ * return values:
+ *   true  - OK
+ *   false - bad name
  */
 
 #include "defines.h"
 
-extern int check_user_name (const char *);
-extern int check_group_name (const char *name);
+extern bool is_valid_user_name (const char *name);
+extern bool is_valid_group_name (const char *name);
 
 #endif
diff --git a/src/groupadd.c b/src/groupadd.c
index 07802452..709884fa 100644
--- a/src/groupadd.c
+++ b/src/groupadd.c
@@ -220,7 +220,7 @@ static void grp_update (void)
  */
 static void check_new_name (void)
 {
-	if (check_group_name (group_name)) {
+	if (is_valid_group_name (group_name)) {
 		return;
 	}
 
diff --git a/src/groupmod.c b/src/groupmod.c
index bdd929af..ddd5eb91 100644
--- a/src/groupmod.c
+++ b/src/groupmod.c
@@ -328,7 +328,7 @@ static void check_new_name (void)
 		return;
 	}
 
-	if (check_group_name (group_newname)) {
+	if (is_valid_group_name (group_newname)) {
 
 		/*
 		 * If the entry is found, too bad.
diff --git a/src/grpck.c b/src/grpck.c
index 02924fce..cb12d6ab 100644
--- a/src/grpck.c
+++ b/src/grpck.c
@@ -497,7 +497,7 @@ static void check_grp_file (int *errors, int *changed)
 		/*
 		 * Check for invalid group names.  --marekm
 		 */
-		if (!check_group_name (grp->gr_name)) {
+		if (!is_valid_group_name (grp->gr_name)) {
 			*errors += 1;
 			printf (_("invalid group name '%s'\n"), grp->gr_name);
 		}
diff --git a/src/newusers.c b/src/newusers.c
index 97a97071..82550dab 100644
--- a/src/newusers.c
+++ b/src/newusers.c
@@ -214,7 +214,7 @@ static int add_group (const char *name, const char *gid, gid_t *ngid, uid_t uid)
 	}
 
 	/* Check if this is a valid group name */
-	if (check_group_name (grent.gr_name) == 0) {
+	if (!is_valid_group_name (grent.gr_name)) {
 		fprintf (stderr,
 		         _("%s: invalid group name `%s'\n"),
 		         Prog, grent.gr_name);
@@ -318,7 +318,7 @@ static int add_user (const char *name, uid_t uid, gid_t gid)
 	struct passwd pwent;
 
 	/* Check if this is a valid user name */
-	if (check_user_name (name) == 0) {
+	if (!is_valid_user_name (name)) {
 		fprintf (stderr,
 		         _("%s: invalid user name `%s'\n"),
 		         Prog, name);
diff --git a/src/pwck.c b/src/pwck.c
index 0b42a86d..d319008c 100644
--- a/src/pwck.c
+++ b/src/pwck.c
@@ -354,7 +354,7 @@ static void check_pw_file (int *errors, int *changed)
 		/*
 		 * Check for invalid usernames.  --marekm
 		 */
-		if (!check_user_name (pwd->pw_name)) {
+		if (!is_valid_user_name (pwd->pw_name)) {
 			printf (_("invalid user name '%s'\n"), pwd->pw_name);
 			*errors += 1;
 		}
diff --git a/src/useradd.c b/src/useradd.c
index b606c90e..b4211769 100644
--- a/src/useradd.c
+++ b/src/useradd.c
@@ -1123,7 +1123,7 @@ static void process_flags (int argc, char **argv)
 			usage ();
 
 		user_name = argv[optind];
-		if (!check_user_name (user_name)) {
+		if (!is_valid_user_name (user_name)) {
 			fprintf (stderr,
 				 _
 				 ("%s: invalid user name '%s'\n"),
diff --git a/src/usermod.c b/src/usermod.c
index c09907a9..e75111a5 100644
--- a/src/usermod.c
+++ b/src/usermod.c
@@ -917,7 +917,7 @@ static void process_flags (int argc, char **argv)
 				Gflg++;
 				break;
 			case 'l':
-				if (!check_user_name (optarg)) {
+				if (!is_valid_user_name (optarg)) {
 					fprintf (stderr,
 						 _("%s: invalid field '%s'\n"),
 						 Prog, optarg);