add missing import
diff --git a/Lib/webbrowser.py b/Lib/webbrowser.py
index 18dc11b..39f9b99 100644
--- a/Lib/webbrowser.py
+++ b/Lib/webbrowser.py
@@ -223,6 +223,7 @@
         cmdline = [self.name] + raise_opt + args
 
         if remote or self.background:
+            import io
             inout = io.open(os.devnull, "r+")
         else:
             # for TTY browsers, we need stdin/out