diff --git a/lib/core_assertions.rb b/lib/core_assertions.rb
index 1e4a67a..07b0cb1 100644
--- a/lib/core_assertions.rb
+++ b/lib/core_assertions.rb
@@ -324,12 +324,12 @@ def assert_no_memory_leak(args, prepare, code, message=nil, limit: 2.0, rss: fal
               end
             rescue Timeout::Error
               timed_out = Time.now
+              in_p.close
               status = begin
                 EnvUtil.terminate(pid, opt.fetch(:signal, :TERM), opt[:pgroup], opt.fetch(:reprieve, 1))
               rescue Errno::ESRCH, Errno::ECHILD
                 warn "child not found: #{pid}: #$!"
               end
-              in_p.close
             end
             stdout = out_reader.value
             if timed_out