diff --git a/pdf.lua b/pdf.lua
index d5ae598..dde733c 100644
--- a/pdf.lua
+++ b/pdf.lua
@@ -16,7 +16,7 @@ PDF.new = function()
 
 	local add = function(obj)
 		table.insert(object, obj)
-		obj.number = table.getn(object)
+		obj.number = #object
 		return obj
 	end
 
@@ -111,7 +111,7 @@ PDF.new = function()
 
 		xref_table_offset = fh:seek()
 		fh:write("xref\n")
-		fh:write(string.format("%d %d\n", 1, table.getn(object)))
+		fh:write(string.format("%d %d\n", 1, #object))
 		for i, obj in ipairs(object) do
 			fh:write(
 			    string.format("%010d %05d n \n", obj.offset, 0)
@@ -122,7 +122,7 @@ PDF.new = function()
 	local write_trailer = function(fh)
 		fh:write("trailer\n")
 		fh:write("<<\n")
-		fh:write(string.format("/Size %d\n", table.getn(object)))
+		fh:write(string.format("/Size %d\n", #object))
 		fh:write("/Root " .. get_ref(catalog_obj) .. "\n")
 		fh:write(">>\n")
 		fh:write("startxref\n")
@@ -167,7 +167,7 @@ PDF.new = function()
 			end
 			
 			table.insert(used_font, font_obj)
-			return "/F" .. table.getn(used_font)
+			return "/F" .. #used_font
 		end
 
 		--