diff --git a/inferium-harvester.lua b/inferium-harvester.lua
index dc9f330..df39604 100644
--- a/inferium-harvester.lua
+++ b/inferium-harvester.lua
@@ -1,3 +1,4 @@
+local utils = require('libs/utils')
 local turtleUtils = require('libs/turtle-utils')
 local config = require('config/harvesting')
 
@@ -27,38 +28,6 @@ local localPlan = nil
 
 -- UTILS
 
-local function sizeof(t)
-  if not t then
-    return 0
-  end
-
-  local size = 0
-  for k,v in pairs(t) do
-    size = size + 1
-  end
-  return size
-end
-
-function difference(a, b)
-  local aa = {}
-  for k,v in pairs(a) do aa[v]=true end
-  for k,v in pairs(b) do aa[v]=nil end
-  local ret = {}
-  local n = 0
-  for k,v in pairs(a) do
-      if aa[v] then n=n+1 ret[n]=v end
-  end
-  return ret
-end
-
-local function shallowClone(t)
-  local res = {}
-  for k,v in pairs(t) do
-    res[k] = v
-  end
-  return res
-end
-
 local function removeFirst(t, x)
   local res = {}
   local removed = false
@@ -74,14 +43,6 @@ local function removeFirst(t, x)
   return res
 end
 
-local function find(t, predicate)
-  for k,v in pairs(t) do
-    if predicate(v, k) then
-      return v, k
-    end
-  end
-end
-
 local function getIndexedCount(t)
   local res = {}
 
@@ -324,7 +285,7 @@ local function removeSeeds(seeds)
     local ok, block = turtle.inspectDown()
     local blockName = block and block.name
 
-    local found = find(stateSeeds, function(seedName) return seedName == getSeedNameFromCropName(blockName) end)
+    local found = utils.find(stateSeeds, function(seedName) return seedName == getSeedNameFromCropName(blockName) end)
 
     if found then
       local digOk = turtle.digDown()
@@ -424,18 +385,18 @@ local function replantProcedure()
     error('cannot fetch the remote plan')
   end
 
-  local seedsToRemove = difference(localPlan, remotePlan)
-  local seedsToPlant = difference(remotePlan, localPlan)
+  local seedsToRemove = utils.difference(localPlan, remotePlan)
+  local seedsToPlant = utils.difference(remotePlan, localPlan)
 
-  if sizeof(seedsToRemove) > 0 then
-    print('nb seeds to remove: ' .. sizeof(seedsToRemove))
+  if utils.sizeof(seedsToRemove) > 0 then
+    print('nb seeds to remove: ' .. utils.sizeof(seedsToRemove))
     removeSeeds(seedsToRemove)
   else
     print('no seeds to remove')
   end
 
-  if sizeof(seedsToPlant) > 0 then
-    print('nb seeds to plants: ' .. sizeof(seedsToPlant))
+  if utils.sizeof(seedsToPlant) > 0 then
+    print('nb seeds to plants: ' .. utils.sizeof(seedsToPlant))
     retrieveSeeds(seedsToPlant)
     replantSeeds()
   else
diff --git a/install.lua b/install.lua
index eac3b21..cd4eae3 100644
--- a/install.lua
+++ b/install.lua
@@ -7,6 +7,7 @@ local LIST_FILES = {
 };
 
 local LIST_LIBS_FILES = {
+  'libs/utils.lua',
   'libs/turtle-utils.lua',
   'libs/robot.lua'
 }
diff --git a/libs/utils.lua b/libs/utils.lua
new file mode 100644
index 0000000..424481a
--- /dev/null
+++ b/libs/utils.lua
@@ -0,0 +1,44 @@
+local utils = {}
+
+utils.sizeof = function(t)
+  if not t then
+    return 0
+  end
+
+  local size = 0
+  for k,v in pairs(t) do
+    size = size + 1
+  end
+  return size
+end
+
+utils.difference = function(a, b)
+  local aa = {}
+  for k,v in pairs(a) do aa[v]=true end
+  for k,v in pairs(b) do aa[v]=nil end
+  local ret = {}
+  local n = 0
+  for k,v in pairs(a) do
+      if aa[v] then n=n+1 ret[n]=v end
+  end
+  return ret
+end
+
+utils.shallowClone = function(t)
+  local res = {}
+  for k,v in pairs(t) do
+    res[k] = v
+  end
+  return res
+end
+
+
+utils.find = function(t, predicate)
+  for k,v in pairs(t) do
+    if predicate(v, k) then
+      return v, k
+    end
+  end
+end
+
+return utils
\ No newline at end of file