diff --git a/poincare/include/poincare/allocation_failure_expression_node.h b/poincare/include/poincare/allocation_failure_expression_node.h
index f83ba76a5..cb381097f 100644
--- a/poincare/include/poincare/allocation_failure_expression_node.h
+++ b/poincare/include/poincare/allocation_failure_expression_node.h
@@ -11,6 +11,8 @@ public:
   // ExpressionNode
   ExpressionNode::Type type() const override { return ExpressionNode::Type::AllocationFailure; }
   // TreeNode
+  void incrementNumberOfChildren(int increment = 1) override {}
+  void decrementNumberOfChildren(int decrement = 1) override {}
   size_t size() const override { return sizeof(AllocationFailureExpressionNode<T>); }
   bool isAllocationFailure() const override { return true; }
   TreeNode * uninitializedStaticNode() const override { assert(false); return nullptr; }
diff --git a/poincare/include/poincare/n_ary_expression_node.h b/poincare/include/poincare/n_ary_expression_node.h
index 4dbd757d1..931db90f5 100644
--- a/poincare/include/poincare/n_ary_expression_node.h
+++ b/poincare/include/poincare/n_ary_expression_node.h
@@ -9,9 +9,8 @@ class NAryExpressionNode : public ExpressionNode { // TODO: VariableArityExpress
 public:
   //Tree
   int numberOfChildren() const override { return m_numberOfChildren; }
-  void incrementNumberOfChildren(int increment = 1) override { /*TODO override for alloc fail ?*/ m_numberOfChildren+= increment; }
+  void incrementNumberOfChildren(int increment = 1) override { m_numberOfChildren+= increment; }
   void decrementNumberOfChildren(int decrement = 1) override {
-    /*TODO override for alloc fail ?*/
     assert(m_numberOfChildren >= decrement);
     m_numberOfChildren-= decrement;
   }