diff --git a/lib/resty/mongol/ll.lua b/lib/resty/mongol/ll.lua
index ec06645..49312c9 100644
--- a/lib/resty/mongol/ll.lua
+++ b/lib/resty/mongol/ll.lua
@@ -31,7 +31,6 @@ local num_to_le_uint = function ( n , bytes )
 	for i=1 , bytes do
 		b [ i ] , n = n % 2^8 , floor ( n / 2^8 )
 	end
-	assert ( n == 0 )
 	return strchar ( unpack ( b ) )
 end
 local num_to_le_int = function ( n , bytes )
@@ -57,7 +56,6 @@ local num_to_be_uint = function ( n , bytes )
 	for i=bytes , 1 , -1 do
 		b [ i ] , n = n % 2^8 , floor ( n / 2^8 )
 	end
-	assert ( n == 0 )
 	return strchar ( unpack ( b ) )
 end
 
diff --git a/lib/resty/mongol/object_id.lua b/lib/resty/mongol/object_id.lua
index fc3f2bb..88f6b52 100755
--- a/lib/resty/mongol/object_id.lua
+++ b/lib/resty/mongol/object_id.lua
@@ -46,20 +46,27 @@ local object_id_mt = {
 }
 
 local machineid
-if hasposix then
-    machineid = posix.uname("%n")
-else
-    machineid = assert(io.popen("uname -n")):read("*l")
+local function get_os_machineid()
+    if hasposix then
+        machineid = posix.uname("%n")
+    else
+        machineid = assert(io.popen("uname -n")):read("*l")
+    end
+    machineid = ngx.md5_bin(machineid):sub(1, 3)
+    return machineid
 end
-machineid = ngx.md5_bin(machineid):sub(1, 3)
 
-local pid = num_to_le_uint(ngx.var.pid, 2)
+local pid
+local function get_os_pid()
+    pid = num_to_le_uint(ngx.var.pid, 2)
+    return pid 
+end
 
 local inc = 0
-local function generate_id ( )
+local function generate_id()
     inc = inc + 1
     -- "A BSON ObjectID is a 12-byte value consisting of a 4-byte timestamp (seconds since epoch), a 3-byte machine id, a 2-byte process id, and a 3-byte counter. Note that the timestamp and counter fields must be stored big endian unlike the rest of BSON"
-    return num_to_be_uint ( os.time ( ) , 4 ) .. machineid .. pid .. num_to_be_uint ( inc , 3 )
+    return num_to_be_uint(os.time(), 4) .. (machineid or get_os_machineid()) .. (pid or get_os_pid()) .. num_to_be_uint(inc, 3)
 end
 
 local function new_object_id(str)