diff -ruN ecasound-2.9.1.orig/configure.ac ecasound-2.9.1/configure.ac
--- ecasound-2.9.1.orig/configure.ac	2014-01-03 11:34:07.000000000 +0100
+++ ecasound-2.9.1/configure.ac	2017-02-25 23:46:30.167878523 +0100
@@ -749,7 +749,7 @@
   rubyecasound_support=no
   ECA_S_RUBY_SITEDIR=""
 else
-  ECA_S_RUBY_SITEDIR="`ruby -e 'require "rbconfig"; include Config; print CONFIG[["sitedir"]] + "/" + CONFIG[["MAJOR"]] + "." + CONFIG[["MINOR"]]'`"
+  ECA_S_RUBY_SITEDIR="`ruby -rrbconfig -e 'print RbConfig::CONFIG[["vendordir"]]'`"
 fi
 
 AC_SUBST(ECA_S_RUBY_SITEDIR)