diff --git a/config.def.h b/config.def.h
index f79db7b..86e4afd 100644
--- a/config.def.h
+++ b/config.def.h
@@ -1,14 +1,14 @@
 /* quark configuration */
 
-static const char servername[] = "127.0.0.1";
-static const char serverport[] = "80";
-static const char docroot[]    = ".";
-static const char docindex[]   = "index.html";
-static const char user[]       = "nobody";
-static const char group[]      = "nogroup";
-static const char cgi_dir[]    = "/var/www/werc-dev/bin";
-static const char cgi_script[] = "./werc.rc";
-static const int  cgi_mode     = 0;
+static const char  servername[] = "127.0.0.1";
+static const char  serverport[] = "80";
+static const char  docroot[]    = ".";
+static const char  docindex[]   = "index.html";
+static const char *user         = "nobody";
+static const char *group        = "nogroup";
+static const char  cgi_dir[]    = "/var/www/werc-dev/bin";
+static const char  cgi_script[] = "./werc.rc";
+static const int   cgi_mode     = 0;
 
 static const MimeType servermimes[] = {
 	{ "html", "text/html; charset=UTF-8" },
diff --git a/quark.c b/quark.c
index 49dfe9b..660a405 100644
--- a/quark.c
+++ b/quark.c
@@ -522,10 +522,12 @@ main(int argc, char *argv[]) {
 			die("usage: quark [-v]\n");
 
 	/* sanity checks */
-	if(!(upwd = getpwnam(user)))
-		die("error: invalid user %s\n", user);
-	if(!(gpwd = getgrnam(group)))
-		die("error: invalid group %s\n", group);
+	if(user)
+		if(!(upwd = getpwnam(user)))
+			die("error: invalid user %s\n", user);
+	if(group)
+		if(!(gpwd = getgrnam(group)))
+			die("error: invalid group %s\n", group);
 
 	signal(SIGCHLD, sighandler);
 	signal(SIGHUP, sighandler);
@@ -573,10 +575,12 @@ main(int argc, char *argv[]) {
 	if(chroot(".") == -1)
 		die("error: chroot .: %s\n", strerror(errno));
 
-	if(setgid(gpwd->gr_gid) == -1)
-		die("error: cannot set group id\n");
-	if(setuid(upwd->pw_uid) == -1)
-		die("error: cannot set user id\n");
+	if(gpwd)
+		if(setgid(gpwd->gr_gid) == -1)
+			die("error: cannot set group id\n");
+	if(upwd)
+		if(setuid(upwd->pw_uid) == -1)
+			die("error: cannot set user id\n");
 
 	if(getuid() == 0)
 		die("error: won't run with root permissions, choose another user\n");