diff --git a/nselib/unittest.lua b/nselib/unittest.lua
index 607869218..88f930cb5 100644
--- a/nselib/unittest.lua
+++ b/nselib/unittest.lua
@@ -348,7 +348,7 @@ end
 --         distinguishability otherwise.
 identical = function(a, b)
   return function(suite)
-    function identical(val1, val2, path)
+    local function _identical(val1, val2, path)
       local table_size = function(tbl)
         local count = 0
         for k in pairs(tbl) do
@@ -381,7 +381,7 @@ identical = function(a, b)
       for k,v in pairs(val1) do
         -- Check that the key's value is identical in both tables, passing
         -- along the path of keys we have taken to get here.
-        local status, note = identical(val1[k], val2[k], string.format('%s["%s"]', path, k))
+        local status, note = _identical(val1[k], val2[k], string.format('%s["%s"]', path, k))
         if not status then
           return false, note
         end
@@ -390,7 +390,7 @@ identical = function(a, b)
       return true
     end
 
-    return identical(a, b, "<top>")
+    return _identical(a, b, "<top>")
   end
 end