diff --git a/poincare/include/poincare/rational.h b/poincare/include/poincare/rational.h
index 636754a68..e5a608b68 100644
--- a/poincare/include/poincare/rational.h
+++ b/poincare/include/poincare/rational.h
@@ -20,7 +20,7 @@ public:
   // Getter
   const Integer numerator() const;
   const Integer denominator() const;
-
+  void setNegative(bool negative) { m_numerator.setNegative(negative); }
   // Expression subclassing
   Type type() const override;
   Expression * clone() const override;