--- ./o/unixfsys.c.orig	2014-09-06 09:45:30.000000000 -0600
+++ ./o/unixfsys.c	2014-09-06 20:00:00.000000000 -0600
@@ -411,11 +411,17 @@ FILE *
 backup_fopen(char *filename, char *option)
 {
 	char backupfilename[MAXPATHLEN];
-	char command[MAXPATHLEN * 2];
+#ifndef HAVE_RENAME
+	char command[MAXPATHLEN * 2 + 4];
+#endif
 
 	strcat(strcpy(backupfilename, filename), ".BAK");
+#ifdef HAVE_RENAME
+	rename(filename, backupfilename);
+#else
 	sprintf(command, "mv %s %s", filename, backupfilename);
 	msystem(command);
+#endif
 	return(fopen(filename, option));
 }
 
@@ -440,6 +446,9 @@ LFD(Lrename_file)(void)
 {
 	char filename[MAXPATHLEN];
 	char newfilename[MAXPATHLEN];
+#ifndef HAVE_RENAME
+	char command[MAXPATHLEN * 2 + 4];
+#endif
 
 	check_arg(2);
 	check_type_or_pathname_string_symbol_stream(&vs_base[0]);