--- ruby-2.2.5/tool/mkconfig.rb.orig	2016-09-19 13:53:05.152982868 +0200
+++ ruby-2.2.5/tool/mkconfig.rb	2016-09-19 14:01:04.182988081 +0200
@@ -79,6 +79,7 @@
     when /^LIBRUBY_D?LD/; next
     when /^RUBY_INSTALL_NAME$/; next vars[name] = (install_name = val).dup if $install_name
     when /^RUBY_SO_NAME$/; next vars[name] = (so_name = val).dup if $so_name
+    when /^(CC|CXX)$/; val.sub!(/ccache /, '')
     when /^arch$/; if val.empty? then val = arch else arch = val end
     when /^sitearch$/; val = '$(arch)' if val.empty?
     end