diff --git a/lib/open3.rb b/lib/open3.rb
index 959181b67d..58245100b4 100644
--- a/lib/open3.rb
+++ b/lib/open3.rb
@@ -190,7 +190,10 @@ module Open3
   module_function :popen2e
 
   def popen_run(cmd, opts, child_io, parent_io) # :nodoc:
-    opts = opts.merge(cmd.pop) if cmd.last.kind_of? Hash
+    if last = Hash.try_convert(cmd.last)
+      opts = opts.merge(last)
+      cmd.pop
+    end
     pid = spawn(*cmd, opts)
     wait_thr = Process.detach(pid)
     child_io.each {|io| io.close }