diff --git a/template/exts.mk.tmpl b/template/exts.mk.tmpl
index 5a72912839..e4706be373 100644
--- a/template/exts.mk.tmpl
+++ b/template/exts.mk.tmpl
@@ -39,6 +39,7 @@ Dir.glob("{ext,.bundle/gems}/*/exts.mk") do |e|
     else
       macros[n] = m | v
     end
+    break if n == "old_extensions"
   end
   if gem
     r = ""