diff --git a/src/tools/add_commit_links.pl b/src/tools/add_commit_links.pl
index 710a6492032..87a6e47e6fe 100755
--- a/src/tools/add_commit_links.pl
+++ b/src/tools/add_commit_links.pl
@@ -50,6 +50,8 @@ sub process_file
 	# Get major version number from the file name.
 	$file =~ m/-(\d+)\./;
 	my $major_version = $1;
+	die "file name $file is not in the expected format\n"
+		unless defined $major_version;
 
 	open(my $fh, '<', $file) || die "could not open file $file: $!\n";
 	open(my $tfh, '>', $tmpfile) || die "could not open file $tmpfile: $!\n";