Make it so you cant jump in air

For now this is how i handle jumping in the game

 void Jump ()
 {
     if (Input.GetButtonDown("Jump") && Grounded)
     {
         rb.AddForce(new Vector2(0f, jumpForce), ForceMode2D.Impulse);
         Grounded = false;
     }
 }
 void OnCollisionEnter2D(Collision2D collision)
 {
     if(collision.gameObject.tag == "Ground")
     {
         Grounded = true;
     }
 }

And if you skim through it you can quite quickly see what the problem is, so basically i set Grounded to false when i jump but if i were to say walk off a ledge it isnt set to false so how could i make it so i cant jump when im in the air?