--- ruby-lapack.orig/ext/extconf.rb
+++ ruby-lapack/ext/extconf.rb
@@ -41,7 +41,7 @@
 
   name = with_config("blas-name","blas_LINUX.a")
   unless have_library(name)
-    lib_path = with_config("blas-lib","/usr/local/lib")
+    lib_path = with_config("blas-lib","/usr/lib")
     _libarg = LIBARG
     LIBARG.replace "#{lib_path}/%s"
     unless have_library(name)
@@ -51,7 +51,7 @@
   end
   name = with_config("lapack-name","lapack_LINUX.a")
   unless have_library(name)
-    lib_path = with_config("lapack-lib","/usr/local/lib")
+    lib_path = with_config("lapack-lib","/usr/lib")
     _libarg = LIBARG
     LIBARG.replace "#{lib_path}/%s"
     unless have_library(name)
@@ -61,17 +61,9 @@
   end
 end
 
-sitearchdir = Config::CONFIG["sitearchdir"]
-dir_config("narray", sitearchdir, sitearchdir)
-gem_path = nil
-begin
-  require "rubygems"
-  if (spec = Gem.source_index.find_name("narray")).any?
-    gem_path = spec.last.full_gem_path
-  end
-rescue LoadError
-end
-unless find_header("narray.h",gem_path) && have_header("narray_config.h")
+archdir = Config::CONFIG["vendorarchdir"]
+dir_config("narray", archdir, archdir)
+unless find_header("narray.h", archdir) && have_header("narray_config.h")
   header_not_found("narray")
 end
 
