1 files changed, 2 insertions, 0 deletions
diff --git a/lib/mkmf.rb b/lib/mkmf.rb
index 846db8bd72..3792da5e4b 100644
--- a/lib/mkmf.rb
+++ b/lib/mkmf.rb
@@ -53,6 +53,8 @@ module MakeMakefile
   $static = nil
   $config_h = '$(arch_hdrdir)/ruby/config.h'
   $default_static = $static
+  $OBJEXT = nil
+  $ignore_error = ''
 
   unless defined? $configure_args
     $configure_args = {}