diff -ur pure-ftpd-1.0.21/pure-config/pure-config.h pure-ftpd-1.0.21.new/pure-config/pure-config.h
--- pure-ftpd-1.0.21/pure-config/pure-config.h	2005-06-18 12:39:55.000000000 +0200
+++ pure-ftpd-1.0.21.new/pure-config/pure-config.h	2009-02-03 15:00:10.358021471 +0100
@@ -82,6 +82,7 @@
 {	NULL,		'\0', /* 'I' */	"MaxIdleTime",			CFG_STR,			(void*) &opt[I],	0 },
 {	NULL,		'\0', /* 'k' */	"MaxDiskUsage",			CFG_STR,			(void*) &opt[I],	0 },
 {	NULL,		'\0', /* 'a' */	"TrustedGID",			CFG_STR,			(void*) &opt[I],	0 },
+{	NULL,		'\0', /* '2' */	"AdditionalGID",		CFG_STR,			(void*) &opt[I],	0 },
 {	NULL,		'\0', /* 'c' */	"MaxClientsNumber",		CFG_STR,			(void*) &opt[I],	0 },
 {	NULL,		'\0', /* 'C' */	"MaxClientsPerIP",		CFG_STR,			(void*) &opt[I],	0 },
 {	NULL,		'\0', /* 'm' */	"MaxLoad",			CFG_STR,			(void*) &opt[I],	0 },
@@ -153,6 +154,7 @@
 	{	"-I",	"--maxidletime="		},
 	{	"-k",	"--maxdiskusage="		},
 	{	"-a",	"--trustedgid="			},
+	{	"-2",	"--additionalgid="		},
 	{	"-c",	"--maxclientsnumber="		},
 	{	"-C",	"--maxclientsperip="		},
 	{	"-m",	"--maxload="			},
diff -ur pure-ftpd-1.0.21/src/ftpd.c pure-ftpd-1.0.21.new/src/ftpd.c
--- pure-ftpd-1.0.21/src/ftpd.c	2009-02-03 15:37:58.538020766 +0100
+++ pure-ftpd-1.0.21.new/src/ftpd.c	2009-02-03 15:41:41.582021928 +0100
@@ -1104,7 +1104,10 @@
 {
 #ifndef NON_ROOT_FTP
 # ifdef HAVE_SETGROUPS
-    if (setgroups(1U, &gid) != 0) {
+    gid_t gids[2];
+    gids[0] = gid;
+    gids[1] = chroot_additionalgid;
+    if (setgroups(want_additionalgid ? 2L : 1L, gids) != 0) {
         return -1;
     }
 # else
@@ -5078,6 +5081,19 @@
             no_truncate = 1;
             break;
         }
+        case '2': {
+            const char *nptr;
+            char *endptr;
+
+            nptr = optarg;
+            endptr = NULL;
+            chroot_additionalgid = strtoul(nptr, &endptr, 0);
+            if (!nptr || !*nptr || !endptr || *endptr) {
+                die(421, LOG_ERR, MSG_CONF_ERR ": " MSG_ILLEGAL_TRUSTED_GID " (XXX: additional): %s" , optarg);
+            }
+	    want_additionalgid = 1;
+            break;
+        }
         case '4': {
             bypass_ipv6 = 1;
             break;
diff -ur pure-ftpd-1.0.21/src/ftpd_p.h pure-ftpd-1.0.21.new/src/ftpd_p.h
--- pure-ftpd-1.0.21/src/ftpd_p.h	2006-02-06 22:57:21.000000000 +0100
+++ pure-ftpd-1.0.21.new/src/ftpd_p.h	2009-02-03 15:35:47.946311240 +0100
@@ -60,7 +60,7 @@
 };
 
 static const char *GETOPT_OPTIONS =
-    "0146"
+    "012:46"
 #ifdef WITH_RFC2640
     "8:9:"
 #endif
@@ -112,6 +112,7 @@
 static struct option long_options[] = {
     { "notruncate", 0, NULL, '0' },    
     { "logpid", 0, NULL, '1' },
+    { "additionalgid", 1, NULL, '2' },
     { "ipv4only", 0, NULL, '4' },
     { "ipv6only", 0, NULL, '6' },    
 #ifdef WITH_RFC2640
diff -ur pure-ftpd-1.0.21/src/globals.h pure-ftpd-1.0.21.new/src/globals.h
--- pure-ftpd-1.0.21/src/globals.h	2006-02-15 09:55:00.000000000 +0100
+++ pure-ftpd-1.0.21.new/src/globals.h	2009-02-03 15:13:13.234021509 +0100
@@ -37,6 +37,8 @@
 GLOBAL0(signed char userchroot);                /* don't chroot() by default for regular users */
 GLOBAL0(signed char chrooted);                     /* if we already chroot()ed */
 GLOBAL0(uid_t chroot_trustedgid);
+GLOBAL(int want_additionalgid, 0);
+GLOBAL0(gid_t chroot_additionalgid);
 GLOBAL0(signed char broken_client_compat);         /* don't enable workarounds by default */
 GLOBAL0(uid_t warez);                    /* don't guard against warez */
 GLOBAL0(signed char debug);                        /* don't give debug output */
--- pure/configuration-file/pure-config.pl.in~	2009-02-03 15:47:24.346020364 +0100
+++ pure/configuration-file/pure-config.pl.in	2009-02-03 15:48:34.678184463 +0100
@@ -64,6 +64,7 @@
 my %numeric_switch_for = (
 	MaxIdleTime		=> "-I",
 	MaxDiskUsage		=> "-k",
+	AdditionalGID		=> "-2",
 	TrustedGID		=> "-a",
 	MaxClientsNumber	=> "-c",
 	MaxClientsPerIP		=> "-C",