diff --git a/util/mdgrep.pl b/util/mdgrep.pl
index fc1475439..9f1560ad9 100644
--- a/util/mdgrep.pl
+++ b/util/mdgrep.pl
@@ -48,11 +48,13 @@
 @const_true = qw/1 TRUE/;
 @const_false = qw/0 FALSE/;
 
+$outfile = "mdgrep.h";
 sub start_file {
 	($rev) = ('$Revision$') =~ m/: (.*) .$/;
-	open(OUT, ">mdgrep.h") || die "open mkgrep.h: $!";
+	open(OUT, ">$outfile") || die "open $outfile: $!";
 	print OUT <<E_O_M;
 /*
+ * $outfile
  * This file generated by mdgrep.pl version $rev.
  * DO NOT EDIT!  Your changes will be lost.
  */