1 files changed, 1 insertions, 1 deletions
diff --git a/lib/mkmf.rb b/lib/mkmf.rb
index 6ce571301..a4f7e5889 100644
--- a/lib/mkmf.rb
+++ b/lib/mkmf.rb
@@ -443,7 +443,7 @@ def create_makefile(target, srcprefix = nil)
         end
       end
     end
-    defflag = "--def=" + deffile
+    defflag = deffile
   end
 
   if RUBY_PLATFORM =~ /mswin32/