A blade closing key system includes a first key piece and a second key piece. The first key piece includes a first finger and an elongated alignment plate. The second key piece includes a second finger and a key slot. The key pieces are installed in a cavity collectively formed by a notch in a blade root and a slot in a rotor disc. The first and second fingers are bent toward each other and engage each other at their ends. Simultaneously, at least a portion of the alignment plate is received in the key slot. During engine operation, the engagement between the alignment plate and the key slot keeps the first and second key pieces aligned. Thus, regardless of the width of either of the two key pieces or the width of the cavity, the fingers remain constantly engaged during engine operation, minimizing the potential for blade liberation.