Index: lib/mruby/build/command.rb
--- lib/mruby/build/command.rb.orig
+++ lib/mruby/build/command.rb
@@ -249,7 +249,7 @@ module MRuby
 
     def initialize(build)
       super
-      @command = "ruby #{MRUBY_ROOT}/tools/lrama/exe/lrama"
+      @command = "${RUBY} #{MRUBY_ROOT}/tools/lrama/exe/lrama"
       @compile_options = %q[-o "%{outfile}" "%{infile}"]
     end
 
