--- a/cmake/modules/FindRuby.cmake
+++ b/cmake/modules/FindRuby.cmake
@@ -86,7 +86,7 @@
       OUTPUT_VARIABLE _RUBY_OUTPUT
       ERROR_QUIET)
     IF(_RUBY_SUCCESS OR NOT _RUBY_OUTPUT)
-      EXECUTE_PROCESS(COMMAND ${RUBY_EXECUTABLE} -r rbconfig -e "print Config::CONFIG['${RBVAR}']"
+      EXECUTE_PROCESS(COMMAND ${RUBY_EXECUTABLE} -r rbconfig -e "print RbConfig::CONFIG['${RBVAR}']"
         RESULT_VARIABLE _RUBY_SUCCESS
         OUTPUT_VARIABLE _RUBY_OUTPUT
         ERROR_QUIET)
@@ -112,7 +112,7 @@
    _RUBY_CONFIG_VAR("sitelibdir" RUBY_SITELIB_DIR)
 
    # vendor_ruby available ?
-   EXECUTE_PROCESS(COMMAND ${RUBY_EXECUTABLE} -r rbconfig -e "print 'true' unless Config::CONFIG['vendorarchdir'].nil?"
+   EXECUTE_PROCESS(COMMAND ${RUBY_EXECUTABLE} -r rbconfig -e "print 'true' unless RbConfig::CONFIG['vendorarchdir'].nil?"
       OUTPUT_VARIABLE RUBY_HAS_VENDOR_RUBY  ERROR_QUIET)
 
    IF(RUBY_HAS_VENDOR_RUBY)