diff --git a/scat/GNUmakefile b/scat/GNUmakefile
index 399947e..704e3d2 100644
--- a/scat/GNUmakefile
+++ b/scat/GNUmakefile
@@ -1,5 +1,4 @@
 include GNUmakevars
-include GNUmakerules
 
 all: scat $(patsubst %.msg, %.cat, $(wildcard *.msg))
 
@@ -15,3 +14,10 @@ clean:
 	rm -f *.cat *.o scat core scat.h
 
 install: $(BINDIR)/scat
+
+GNUmakevars: GNUmakevars.sh
+	sh ./$^ > $@
+GNUmakerules: GNUmakerules.sh
+	sh ./$^ > $@
+
+include GNUmakerules
diff --git a/scat/GNUmakerules.sh b/scat/GNUmakerules.sh
new file mode 100755
index 0000000..952629f
--- /dev/null
+++ b/scat/GNUmakerules.sh
@@ -0,0 +1,5 @@
+#!/bin/sh
+echo "\$(BINDIR)/%: %"
+echo -e "\tcp \$^ \$@"
+echo "\$(MAN1DIR)/%: %"
+echo -e "\tcp \$^ \$@"
diff --git a/scat/GNUmakevars.sh b/scat/GNUmakevars.sh
new file mode 100755
index 0000000..1443f83
--- /dev/null
+++ b/scat/GNUmakevars.sh
@@ -0,0 +1,15 @@
+#!/bin/sh
+prefix=${prefix:-/usr/local}
+echo "BINDIR=$prefix/bin"
+
+for i in "$prefix/share/man/man1" "$prefix/man/man1"
+do
+	if [ -d "$i" -a -w "$i" ]
+	then
+		echo "MAN1DIR=$i"
+		break;
+	fi
+done
+
+echo
+echo "all:"