--- shadow-4.0.18.1/src/useradd.c.gid	2006-11-04 14:09:53.000000000 +0100
+++ shadow-4.0.18.1/src/useradd.c	2006-11-04 14:15:09.000000000 +0100
@@ -207,11 +207,8 @@
 	char *errptr;
 
 	gid = strtol (grname, &errptr, 10);
-	if (*errptr || errno == ERANGE || gid < 0) {
-		fprintf (stderr,
-			 _("%s: invalid numeric argument '%s'\n"), Prog, grname);
-		exit (E_BAD_ARG);
-	}
+	if (*grname != '\0' && *errptr == '\0' && errno != ERANGE && gid >= 0)
+		return getgrgid (gid);
 	return getgrnam (grname);
 }
 
--- shadow-4.0.18.1/src/usermod.c.gid	2006-11-04 14:15:23.000000000 +0100
+++ shadow-4.0.18.1/src/usermod.c	2006-11-04 14:16:42.000000000 +0100
@@ -166,11 +166,8 @@
 	char *errptr;
 
 	val = strtol (grname, &errptr, 10);
-	if (*errptr || errno == ERANGE || val < 0) {
-		fprintf (stderr, _("%s: invalid numeric argument '%s'\n"), Prog,
-			 grname);
-		exit (E_BAD_ARG);
-	}
+	if (*grname != '\0' && *errptr == '\0' && errno != ERANGE && val >= 0)
+		return getgrgid (val);
 	return getgrnam (grname);
 }