diff --git a/nse_main.lua b/nse_main.lua
index 653a751d3..cf81d9ad7 100644
--- a/nse_main.lua
+++ b/nse_main.lua
@@ -843,7 +843,7 @@ local function get_chosen_scripts (rules)
   local name_script = {};
   for i, script in ipairs(chosen_scripts) do
     assert(name_script[script.short_basename] == nil,
-      ("duplicate script ID: '%s'"):formt(script.short_basename));
+      ("duplicate script ID: '%s'"):format(script.short_basename));
     name_script[script.short_basename] = script;
   end
   local chain = {}; -- chain of script names