--- mailx-8.1.1/popen.c.nopanic	Thu Feb  3 16:47:13 2000
+++ mailx-8.1.1/popen.c	Thu Feb  3 16:48:09 2000
@@ -180,6 +180,8 @@
 	sigset_t nset, oset;
 
 	i = file_pid(ptr);
+	if(i < 0) return 0;
+
 	unregister_file(ptr);
 	(void) fclose(ptr);
 	sigemptyset(&nset);
@@ -242,8 +244,7 @@
 	for (p = fp_head; p; p = p->link)
 		if (p->fp == fp)
 			return (p->pid);
-	panic("Invalid file pointer");
-	/*NOTREACHED*/
+	return -1;
 }
 
 /*