diff --git a/ngcp/utils.lua b/ngcp/utils.lua
index 281d4ad..cad5991 100644
--- a/ngcp/utils.lua
+++ b/ngcp/utils.lua
@@ -142,10 +142,13 @@ range = function (i, to, inc)
   return function () if i == to then return nil end i = i + inc return i, i end
 end
 
-function table.shift(t, positions)
+function table.shift(t, position)
   local k, v
   local res = {}
-  for k in range(1, positions % #t) do
+  local p = position % #t
+
+  if p == 0 then return end
+  for k in range(1, p) do
     v = table.remove(t, k-#res)
     table.insert(res, v)
   end
diff --git a/tests/utils.lua b/tests/utils.lua
index b8f28bd..0815d8a 100644
--- a/tests/utils.lua
+++ b/tests/utils.lua
@@ -83,9 +83,22 @@ TestUtils = {} --class
     end
 
     function TestUtils:test_table_shift2()
-        assertEquals(self.simple_list, {1,2,3})
-        table.shift(self.simple_list, 4)
-        assertEquals(self.simple_list, {2,3,1})
+        local tmp = table.deepcopy(self.simple_list)
+        assertEquals(tmp, {1,2,3})
+        table.shift(tmp, 0)
+        assertEquals(tmp, {1,2,3})
+        tmp = table.deepcopy(self.simple_list)
+        table.shift(tmp, 1)
+        assertEquals(tmp, {2,3,1})
+        tmp = table.deepcopy(self.simple_list)
+        table.shift(tmp, 2)
+        assertEquals(tmp, {3,1,2})
+        tmp = table.deepcopy(self.simple_list)
+        table.shift(tmp, 3)
+        assertEquals(tmp, {1,2,3})
+        tmp = table.deepcopy(self.simple_list)
+        table.shift(tmp, 4)
+        assertEquals(tmp, {2,3,1})
     end
 
     function TestUtils:test_table_tostring()