--- ext/rubycocoa/extconf.rb.in.orig	2013-10-12 14:05:05.000000000 -0500
+++ ext/rubycocoa/extconf.rb.in	2021-08-02 00:35:47.000000000 -0500
@@ -37,3 +37,13 @@
 create_makefile('rubycocoa')
 command "mv -f Makefile Makefile.bak"
 command "sed -e 's/-no-cpp-precomp//' -e 's/-no-precomp//' Makefile.bak > Makefile"
+
+# if `make' is not MacOSX's make, make do not know about ".m"
+File.open('Makefile', 'a') do |f|
+  f.write <<EOS
+
+.m.o:
+	$(CC) $(INCFLAGS) $(CPPFLAGS) $(CFLAGS) -c $<
+
+EOS
+end