diff --git a/time_t/GNUmakefile b/time_t/GNUmakefile
index c9cfc71..d3625a5 100644
--- a/time_t/GNUmakefile
+++ b/time_t/GNUmakefile
@@ -12,7 +12,7 @@ install: $(BINDIR)/time_t
 
 GNUmakevars: GNUmakevars.sh
 	sh ./$^ > $@
-GNUmakerules: GNUmakerules.sh
-	sh ./$^ > $@
+GNUmakerules: GNUmakerules.pl
+	perl ./$^ > $@
 
 include GNUmakerules
diff --git a/time_t/GNUmakerules.pl b/time_t/GNUmakerules.pl
new file mode 100755
index 0000000..8f30daa
--- /dev/null
+++ b/time_t/GNUmakerules.pl
@@ -0,0 +1,8 @@
+#!/usr/bin/perl
+use warnings;
+use strict;
+
+print "\$(BINDIR)/%: %\n";
+print "\tcp \$^ \$@\n";
+print "\$(MAN1DIR)/%: %\n";
+print "\tcp \$^ \$@\n";
diff --git a/time_t/GNUmakerules.sh b/time_t/GNUmakerules.sh
deleted file mode 100755
index 952629f..0000000
--- a/time_t/GNUmakerules.sh
+++ /dev/null
@@ -1,5 +0,0 @@
-#!/bin/sh
-echo "\$(BINDIR)/%: %"
-echo -e "\tcp \$^ \$@"
-echo "\$(MAN1DIR)/%: %"
-echo -e "\tcp \$^ \$@"