diff --git a/poincare/include/poincare/n_ary_expression.h b/poincare/include/poincare/n_ary_expression.h
index 814e106dd..bc30ee7a1 100644
--- a/poincare/include/poincare/n_ary_expression.h
+++ b/poincare/include/poincare/n_ary_expression.h
@@ -3,6 +3,8 @@
 
 #include <poincare/expression.h>
 
+// NAryExpressions are additions and multiplications
+
 namespace Poincare {
 
 class NAryExpressionNode : public ExpressionNode { // TODO: VariableArityExpressionNode?