diff --git a/src/andromede/simulation/linearize.py b/src/andromede/simulation/linearize.py
index f1be143..13b5372 100644
--- a/src/andromede/simulation/linearize.py
+++ b/src/andromede/simulation/linearize.py
@@ -11,7 +11,7 @@
 # This file is part of the Antares project.
 
 from abc import ABC, abstractmethod
-from dataclasses import Field, dataclass
+from dataclasses import dataclass
 from typing import List, Optional
 
 from andromede.expression import (
@@ -20,8 +20,6 @@
     ExpressionVisitor,
     MultiplicationNode,
     NegationNode,
-    ValueProvider,
-    resolve_parameters,
 )
 from andromede.expression.expression import (
     AllTimeSumNode,
@@ -47,7 +45,7 @@
     TimeSumNode,
     VariableNode,
 )
-from andromede.expression.visitor import ExpressionVisitorOperations, T, visit
+from andromede.expression.visitor import visit
 from andromede.simulation.linear_expression import LinearExpression, Term, TermKey
 
 
@@ -85,15 +83,6 @@ def to_term(self) -> Term:
         )
 
 
-def generate_key(term: MutableTerm) -> TermKey:
-    return TermKey(
-        term.component_id,
-        term.variable_name,
-        term.time_index,
-        term.scenario_index,
-    )
-
-
 @dataclass
 class LinearExpressionData:
     terms: List[MutableTerm]
@@ -102,7 +91,7 @@ class LinearExpressionData:
     def build(self) -> LinearExpression:
         res_terms = {}
         for t in self.terms:
-            k = generate_key(t)
+            k = t.to_key()
             if k in res_terms:
                 current_t = res_terms[k]
                 current_t.coefficient += t.coefficient
@@ -143,9 +132,13 @@ def multiplication(self, node: MultiplicationNode) -> LinearExpressionData:
         if not lhs.terms:
             multiplier = lhs.constant
             actual_expr = rhs
-        else:
+        elif not rhs.terms:
             multiplier = rhs.constant
             actual_expr = lhs
+        else:
+            raise ValueError(
+                "At least one operand of a multiplication must be a constant expression."
+            )
         actual_expr.constant *= multiplier
         for t in actual_expr.terms:
             t.coefficient *= multiplier
@@ -154,6 +147,10 @@ def multiplication(self, node: MultiplicationNode) -> LinearExpressionData:
     def division(self, node: DivisionNode) -> LinearExpressionData:
         lhs = visit(node.left, self)
         rhs = visit(node.right, self)
+        if rhs.terms:
+            raise ValueError(
+                "The second operand of a division must be a constant expression."
+            )
         divider = rhs.constant
         actual_expr = lhs
         actual_expr.constant /= divider
diff --git a/tests/unittests/expressions/test_linearization.py b/tests/unittests/expressions/test_linearization.py
index 2895b27..7b14eb3 100644
--- a/tests/unittests/expressions/test_linearization.py
+++ b/tests/unittests/expressions/test_linearization.py
@@ -1,26 +1,26 @@
 from unittest.mock import Mock
 
 import pytest
+from pydantic._internal._validators import pattern_bytes_validator
+from unittests.expressions.test_expressions import StructureProvider
 
-from andromede.expression import ExpressionNode, var, LiteralNode
+from andromede.expression import ExpressionNode, LiteralNode, literal, var
 from andromede.expression.expression import (
-    comp_var,
-    comp_param,
     ComponentVariableNode,
+    NoScenarioIndex,
+    ProblemVariableNode,
+    TimeShift,
+    comp_param,
+    comp_var,
+    problem_var,
 )
 from andromede.expression.operators_expansion import (
-    expand_operators,
     ProblemDimensions,
     ProblemIndex,
+    expand_operators,
 )
-from andromede.simulation.linear_expression import (
-    LinearExpression,
-    Term,
-)
-from andromede.simulation.linearize import linearize_expression, ParameterGetter
-from unittests.expressions.test_expressions import (
-    StructureProvider,
-)
+from andromede.simulation.linear_expression import LinearExpression, Term
+from andromede.simulation.linearize import ParameterGetter, linearize_expression
 
 P = comp_param("c", "p")
 X = comp_var("c", "x")
@@ -111,7 +111,19 @@ def test_linearization_of_nested_time_operations(
     assert _expand_and_linearize(expr, dimensions, index, params) == expected
 
 
-# def test_expansion_and_linearization():
-#     param_provider = ComponentEvaluationContext()
-#     with pytest.raises(ValueError):
-#         linearize_expression(expr, structure_provider, value_provider)
+def test_invalid_multiplication() -> None:
+    params = Mock(spec=ParameterGetter)
+
+    x = problem_var("c", "x", time_index=TimeShift(0), scenario_index=NoScenarioIndex())
+    expression = x * x
+    with pytest.raises(ValueError, match="constant"):
+        linearize_expression(expression, 0, 0, params)
+
+
+def test_invalid_division() -> None:
+    params = Mock(spec=ParameterGetter)
+
+    x = problem_var("c", "x", time_index=TimeShift(0), scenario_index=NoScenarioIndex())
+    expression = literal(1) / x
+    with pytest.raises(ValueError, match="constant"):
+        linearize_expression(expression, 0, 0, params)