diff --git a/nselib/url.lua b/nselib/url.lua
index 24b2c3ae8..9f8bb181b 100644
--- a/nselib/url.lua
+++ b/nselib/url.lua
@@ -437,7 +437,7 @@ get_default_scheme_schemes = invert(get_default_port_ports)
 -----------------------------------------------------------------------------
 function get_default_scheme (port)
   local number = (type(port) == "number") and port or port.number
-  return get_default_scheme_schemes[port]
+  return get_default_scheme_schemes[number]
 end
 
 if not unittest.testing() then