diff --git a/ext/extmk.rb b/ext/extmk.rb
index 597fc78..8fad2cc 100755
--- a/ext/extmk.rb
+++ b/ext/extmk.rb
@@ -409,7 +409,6 @@ else
 end
 $ruby << " -I'$(topdir)'"
 unless CROSS_COMPILING
-  $ruby << " -I'$(top_srcdir)/lib'"
   $ruby << " -I'$(extout)/$(arch)' -I'$(extout)/common'" if $extout
   ENV["RUBYLIB"] = "-"
 end