diff --git a/inspect.lua b/inspect.lua
index b7107d4..d6c159a 100644
--- a/inspect.lua
+++ b/inspect.lua
@@ -31,6 +31,10 @@ local inspect ={
 inspect.KEY       = setmetatable({}, {__tostring = function() return 'inspect.KEY' end})
 inspect.METATABLE = setmetatable({}, {__tostring = function() return 'inspect.METATABLE' end})
 
+local rawlen = rawlen or function(t)
+  return #t
+end
+
 -- Apostrophizes the string if it has quotes, but not aphostrophes
 -- Otherwise, it returns a regular quoted string
 local function smartQuote(str)
@@ -84,7 +88,7 @@ local function sortKeys(a, b)
 end
 
 local function getNonSequentialKeys(t)
-  local keys, length = {}, #t
+  local keys, length = {}, rawlen(t)
   for k,_ in pairs(t) do
     if not isSequenceKey(k, length) then table.insert(keys, k) end
   end
@@ -232,7 +236,7 @@ function Inspector:putTable(t)
     if self.tableAppearances[t] > 1 then self:puts('<', self:getId(t), '>') end
 
     local nonSequentialKeys = getNonSequentialKeys(t)
-    local length            = #t
+    local length            = rawlen(t)
     local mt                = getmetatable(t)
     local toStringResult    = getToStringResultSafely(t, mt)