--- Rakefile
+++ Rakefile	2024-06-19 03:55:49.000000000 +0800
@@ -5,7 +5,7 @@
   src = %w[array.c data.c index.c math.c narray.c rand.c struct.c].
     map{|s| File.join(dir,s)} +
     [File.join(dir,"t_*.c"), "lib/numo/narray/extra.rb"]
-  sh "cd ext/numo/narray; ruby extconf.rb; make src"
+  sh "cd ext/numo/narray; @RUBY@ extconf.rb; make src"
   sh "rm -rf yard .yardoc; yard doc -o yard -m markdown -r README.md #{src.join(' ')}"
 end
 
--- ext/numo/narray/depend.erb
+++ ext/numo/narray/depend.erb	2024-06-19 04:14:53.000000000 +0800
@@ -21,7 +21,7 @@
      type_c << c = "t_"+File.basename(s,".rb")+".c"
 %>
 <%=c%>: <%=s%> $(DEPENDS)
-	ruby $(COGEN) -l -o $@ <%=s%>
+	@RUBY@ $(COGEN) -l -o $@ <%=s%>
 <% end %>
 
 src : <%= type_c.join(" ") %>