Index: test/dl/test_base.rb
===================================================================
--- test/dl/test_base.rb	(revision 23030)
+++ test/dl/test_base.rb	(working copy)
@@ -25,7 +25,7 @@
   libm_so = File.join(libdir, "libm.so.6")
 when /mingw/, /mswin/
   require "rbconfig"
-  libc_so = libm_so = RbConfig::CONFIG["RUBY_SO_NAME"].split(/-/, 2)[0] + ".dll"
+  libc_so = libm_so =  RbConfig::CONFIG["sitearch"].split(/-/, 2)[1] + ".dll"
 when /darwin/
   libc_so = "/usr/lib/libc.dylib"
   libm_so = "/usr/lib/libm.dylib"