diff --git a/ext/or-tools/linear.cpp b/ext/or-tools/linear.cpp
index 8ebf163..72fc632 100644
--- a/ext/or-tools/linear.cpp
+++ b/ext/or-tools/linear.cpp
@@ -47,10 +47,7 @@ namespace Rice::detail
 void init_linear(Rice::Module& m) {
   Rice::define_class_under<LinearRange>(m, "LinearRange");
 
-  auto rb_cLinearExpr = Rice::define_class_under<LinearExpr>(m, "LinearExpr");
-  rb_cLinearExpr.define_constructor(Rice::Constructor<LinearExpr>());
-
-  Rice::define_class_under<MPVariable, LinearExpr>(m, "MPVariable")
+  Rice::define_class_under<MPVariable>(m, "MPVariable")
     .define_method("name", &MPVariable::name)
     .define_method("solution_value", &MPVariable::solution_value);
 
diff --git a/lib/or-tools.rb b/lib/or-tools.rb
index 884d571..300d74c 100644
--- a/lib/or-tools.rb
+++ b/lib/or-tools.rb
@@ -5,6 +5,7 @@
 require_relative "or_tools/comparison"
 require_relative "or_tools/comparison_operators"
 require_relative "or_tools/bool_var"
+require_relative "or_tools/linear_expr"
 require_relative "or_tools/constant"
 require_relative "or_tools/cp_model"
 require_relative "or_tools/cp_solver"
@@ -12,7 +13,6 @@
 require_relative "or_tools/int_var"
 require_relative "or_tools/knapsack_solver"
 require_relative "or_tools/linear_constraint"
-require_relative "or_tools/linear_expr"
 require_relative "or_tools/mp_variable"
 require_relative "or_tools/product_cst"
 require_relative "or_tools/routing_index_manager"
diff --git a/lib/or_tools/linear_expr.rb b/lib/or_tools/linear_expr.rb
index 3d05657..015da13 100644
--- a/lib/or_tools/linear_expr.rb
+++ b/lib/or_tools/linear_expr.rb
@@ -1,5 +1,5 @@
 module ORTools
-  class LinearExpr
+  module LinearExprMethods
     def solution_value
       coeffs.sum { |var, coeff| var.solution_value * coeff }
     end
@@ -82,4 +82,8 @@ def coerce(other)
       end
     end
   end
+
+  class LinearExpr
+    include LinearExprMethods
+  end
 end
diff --git a/lib/or_tools/mp_variable.rb b/lib/or_tools/mp_variable.rb
index b9b2ad5..e8572f7 100644
--- a/lib/or_tools/mp_variable.rb
+++ b/lib/or_tools/mp_variable.rb
@@ -1,5 +1,7 @@
 module ORTools
-  class MPVariable < LinearExpr
+  class MPVariable
+    include LinearExprMethods
+
     def add_self_to_coeff_map_or_stack(coeffs, multiplier, stack)
       coeffs[self] += multiplier
     end