diff --git a/pymath/calculus/polynom.py b/pymath/calculus/polynom.py
index c0d43d2..163bcbf 100644
--- a/pymath/calculus/polynom.py
+++ b/pymath/calculus/polynom.py
@@ -146,9 +146,6 @@ class Polynom(AbstractPolynom):
         3 h^{  2 } + 8 h + 6
         >>> R = P(Q)
         """
-        # if isNumerand(value) or Expression.isExpression(value):
-        #    postfix_exp = [value if i==self._letter else i for i in self.postfix_tokens]
-        # else:
         postfix_exp = [
             Expression(value) if i == self._letter else i for i in self.postfix_tokens]
 
diff --git a/pymath/calculus/test/test_polynom.py b/pymath/calculus/test/test_polynom.py
index 04ef823..7a30d89 100644
--- a/pymath/calculus/test/test_polynom.py
+++ b/pymath/calculus/test/test_polynom.py
@@ -8,6 +8,7 @@ from pymath.calculus.polynom import Polynom
 from pymath.calculus.fraction import Fraction
 from pymath.calculus.expression import Expression
 from pymath.calculus.render import txt
+from pymath.calculus.operator import op
 
 
 class TestPolynom(unittest.TestCase):
@@ -69,45 +70,37 @@ class TestPolynom(unittest.TestCase):
 
     def test_postfix(self):
         p = Polynom([1, 2, 3])
-        #ans = [1, 2, "x", "*", "+", 3, "x", 2, "^", "*", "+"]
-        ans = [3, 'x', 2, '^', '*', 2, 'x', '*', '+', 1, '+']
+        ans = [3, 'x', 2, op.pw, op.mul, 2, 'x', op.mul, op.add, 1, op.add]
         self.assertEqual(ans, p.postfix_tokens)
 
     def test_postfix_monom(self):
         p = Polynom([0, 2])
-        ans = [2, "x", "*"]
+        ans = [2, "x", op.mul]
         self.assertEqual(ans, p.postfix_tokens)
 
     def test_postfix_0_coef(self):
         p = Polynom([0, 2, 0, 4])
-        #ans = [2, "x", "*", 4, "x", 3, "^", "*", "+"]
-        ans = [4, 'x', 3, '^', '*', 2, 'x', '*', '+']
+        ans = [4, 'x', 3, op.pw, op.mul, 2, 'x', op.mul, op.add]
         self.assertEqual(ans, p.postfix_tokens)
 
     def test_postfix_1_coef(self):
         p = Polynom([0, 1, 1])
-        #ans = ["x", "x", 2, "^", "+"]
-        ans = ["x", 2, "^", "x", "+"]
+        ans = ["x", 2, op.pw, "x", op.add]
         self.assertEqual(ans, p.postfix_tokens)
 
     def test_postfix_neg_coef(self):
-        # TODO: Choix arbitraire (vis à vis des + et des -) il faudra faire en
-        # fonction de render |sam. juin 14 09:45:55 CEST 2014
         p = Polynom([-1, -2, -3])
-        #ans = [-1, -2, "x", "*", "+", -3, "x", 2, "^", "*", "+"]
-        ans = [3, 'x', 2, '^', '*', '-', 2, 'x', '*', '-', 1, '-']
+        ans = [3, 'x', 2, op.pw, op.mul, op.sub1, 2, 'x', op.mul, op.sub, 1, op.sub]
         self.assertEqual(ans, p.postfix_tokens)
 
     def test_postfix_multi_coef(self):
         p = Polynom([1, [2, 3], 4])
-        #ans = [1, 2, "x", "*", "+", 3, "x", "*", "+", 4, "x", 2, "^", "*", "+"]
-        ans = [4, 'x', 2, '^', '*', 2, 'x', '*', '+', 3, 'x', '*', '+', 1, '+']
+        ans = [4, 'x', 2, op.pw, op.mul, 2, 'x', op.mul, op.add, 3, 'x', op.mul, op.add, 1, op.add]
         self.assertEqual(ans, p.postfix_tokens)
 
     def test_postfix_arithm_coef(self):
         p = Polynom([1, Expression([2, 3, "+"]), 4])
-        #ans = [1, 2, 3, "+", "x", "*", "+", 4, "x", 2, "^", "*", "+"]
-        ans = [4, 'x', 2, '^', '*', 2, 3, '+', 'x', '*', '+', 1, '+']
+        ans = [4, 'x', 2, op.pw, op.mul, 2, 3, op.add, 'x', op.mul, op.add, 1, op.add]
         self.assertEqual(ans, p.postfix_tokens)
 
     def test_reduce_nilpo(self):