diff --git a/tool/mkrunnable.rb b/tool/mkrunnable.rb
index 0bdc7784bd..ef358e2425 100755
--- a/tool/mkrunnable.rb
+++ b/tool/mkrunnable.rb
@@ -34,7 +34,10 @@ vendordir = config["vendordir"]
 rubylibdir = config["rubylibdir"]
 rubyarchdir = config["rubyarchdir"]
 archdir = "#{extout}/#{arch}"
-exedir = libdirname == "archlibdir" ? "#{config["libexecdir"]}/#{arch}" : bindir
+exedir = bindir
+if libdirname == "archlibdir"
+  exedir = exedir.sub(%r[/\K(?=[^/]+\z)]) {extout+"/"}
+end
 [exedir, libdir, archdir].uniq.each do |dir|
   File.directory?(dir) or mkdir_p(dir)
 end
diff --git a/tool/rbinstall.rb b/tool/rbinstall.rb
index 9a0d20b746..c550a9485f 100755
--- a/tool/rbinstall.rb
+++ b/tool/rbinstall.rb
@@ -367,11 +367,7 @@ goruby_install_name = "go" + ruby_install_name
 
 bindir = CONFIG["bindir", true]
 if CONFIG["libdirname"] == "archlibdir"
-  libexecdir = MAKEFILE_CONFIG["archlibdir"].dup
-  unless libexecdir.sub!(/\$\(lib\K(?=dir\))/) {"exec"}
-    libexecdir = "$(libexecdir)/$(arch)"
-  end
-  archbindir = RbConfig.expand(libexecdir)
+  archbindir = bindir.sub(%r[/\K(?=[^/]+\z)]) {CONFIG["target"] + "/"}
 end
 libdir = CONFIG[CONFIG.fetch("libdirname", "libdir"), true]
 rubyhdrdir = CONFIG["rubyhdrdir", true]