diff --git a/ext/-test-/auto_ext.rb b/ext/-test-/auto_ext.rb
index 158d5d8f..281fe1d3 100644
--- a/ext/-test-/auto_ext.rb
+++ b/ext/-test-/auto_ext.rb
@@ -6,5 +6,6 @@ def auto_ext(feat = $0[%r[/ext/(-test-/.*)/extconf.rb\z], 1], inc: false)
   inits.delete("init")
   inits.map! {|s|"X(#{s})"}
   $defs << "'-DTEST_INIT_FUNCS(X)=\"#{inits.join(' ')}\"'"
+  create_header
   create_makefile(feat)
 end