diff -Nur gksu-1.3.7/gksu/gksuexec.c gksu-1.3.7.new/gksu/gksuexec.c
--- gksu-1.3.7/gksu/gksuexec.c	2005-10-19 19:00:48.000000000 +0200
+++ gksu-1.3.7.new/gksu/gksuexec.c	2006-04-30 11:44:36.000000000 +0200
@@ -19,6 +19,7 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#define __USE_GNU
 #include <unistd.h>
 #include <string.h>
 #include <errno.h>
@@ -26,6 +27,7 @@
 #include <sys/types.h>
 #include <gtk/gtk.h>
 #include <locale.h>
+#include <grp.h>
 
 #include <gksu.h>
 
@@ -35,6 +37,7 @@
 #include "util.h"
 
 #define GKSU_CMD (PREFIX "/bin/gksu")
+#define GKSUDO_CMD (PREFIX "/bin/gksudo")
 
 void
 run_gksu (GksuContext conf)
@@ -42,7 +45,21 @@
   gchar **cmd = g_malloc (sizeof(gchar*)*7);
   gint i = 0;
 
-  cmd[i] = g_strdup (GKSU_CMD); i++;
+  // the user root is special on ubuntu
+  if(strcmp (conf.user, "root") == 0) 
+    {
+      cmd[i] = g_strdup (GKSUDO_CMD); i++;
+    }
+  else
+    {
+      // if the user is in the admin group we use sudo
+      struct group *grp = getgrnam("admin");
+      if(group_member(grp->gr_gid)) {
+	cmd[i] = g_strdup (GKSUDO_CMD); i++;
+      } else {
+	cmd[i] = g_strdup (GKSU_CMD); i++;
+      }
+    }
   cmd[i] = g_strdup ("--user"); i++;
   cmd[i] = g_strdup (conf.user); i++;