diff -puNr psmisc-21.5.orig/src/pstree.c psmisc-21.5/src/pstree.c
--- psmisc-21.5.orig/src/pstree.c	Fri Feb 18 23:24:38 2005
+++ psmisc-21.5/src/pstree.c	Fri Feb 18 23:34:48 2005
@@ -551,6 +551,7 @@ dump_by_user (PROC * current, uid_t uid)
 {
   const CHILD *walk;
 
+  if (!current) return;
   if (current->uid == uid)
     {
       if (dumped)
@@ -890,11 +891,23 @@ main (int argc, char **argv)
   read_proc ();
   for (current = find_proc (highlight); current; current = current->parent)
     current->highlight = 1;
-  if (!pw)
-    dump_tree (find_proc (pid), 0, 1, 1, 1, 0, 0);
+  if (!pw) {
+    PROC *root = find_proc(pid);
+    if (root) {
+      dump_tree (find_proc (pid), 0, 1, 1, 1, 0, 0);
+    }
+    else
+      {
+        PROC *walk;
+        for (walk = list; walk; walk = walk->next)
+          if (!walk->parent) dump_tree(walk, 0, 1, 1, 1, 0, 0);
+      }
+  }
   else
     {
-      dump_by_user (find_proc (1), pw->pw_uid);
+      PROC *walk;
+      for (walk = list; walk; walk = walk->next)
+        if (!walk->parent) dump_by_user (walk, pw->pw_uid);
       if (!dumped)
 	{
 	  fprintf (stderr, _("No processes found.\n"));