diff --git a/rubygem-ffi.spec b/rubygem-ffi.spec
index 0110016..32ca062 100644
--- a/rubygem-ffi.spec
+++ b/rubygem-ffi.spec
@@ -64,6 +64,8 @@ Test::Unit or RSpec files, useful for developers.
 %install
 %gem_install -f
 %gem_cleanup
+# MANUAL
+rm -r %{buildroot}%{_libdir}/ruby/gems/%{rb_ver}/gems/%{mod_full_name}/ext
 
 %files
 %defattr(-,root,root,-)