Fastening system configured to fasten at least one tank intended to contain liquid hydrogen, the tank or tanks having a centre of gravity, the fastening system being intended to be integrated into a fuselage body of an aircraft, the fastening system being linked to an orthogonal frame of reference defined by an axis X intended to be parallel to a longitudinal axis of the fuselage body, a horizontal axis Y and a vertical axis Z, the fastening system having a vertical plane of symmetry perpendicular to the axis Y, the fastening system comprising: - a longitudinal box extending parallel to the axis X and having a plane of symmetry that is coincident with the vertical plane of symmetry, - a plurality of upper formers perpendicular to the axis X and fastened to an upper end of the longitudinal box, the upper formers of the plurality of upper formers being distributed along the axis X, the plurality of upper formers comprising at least two fastening upper formers each having two fastening devices on either side of the longitudinal box in order to each connect a first fastening point of at least one tank to the fastening upper formers by a sliding pivot connection of pivot axis parallel to the axis X, the pivot axis being configured to be comprised in a plane perpendicular to the axis Y comprising the centre of gravity of the tank, - a plurality of lower formers perpendicular to the axis X and fastened to a lower end of the longitudinal box, the lower formers of the plurality of lower formers being distributed along the axis X, the plurality of lower formers comprising at least one fastening lower former having two second fastening devices on either side of the longitudinal box in order to each connect a second fastening point of the tank or tanks to the fastening lower former or formers, the first fastening point and the second fastening point of a tank being capable of being comprised in a plane perpendicular to the axis Y and comprising the centre of gravity of said tank. - a longitudinal box extending parallel to the axis X and having a plane of symmetry that is coincident with the vertical plane of symmetry, - a plurality of upper formers perpendicular to the axis X and fastened to an upper end of the longitudinal box, the upper formers of the plurality of upper formers being distributed along the axis X, the plurality of upper formers comprising at least two fastening upper formers each having two fastening devices on either side of the longitudinal box in order to each connect a first fastening point of at least one tank to the fastening upper formers by a sliding pivot connection of pivot axis parallel to the axis X, the pivot axis being configured to be comprised in a plane perpendicular to the axis Y comprising the centre of gravity of the tank, - a plurality of lower formers perpendicular to the axis X and fastened to a lower end of the longitudinal box, the lower formers of the plurality of lower formers being distributed along the axis X, the plurality of lower formers comprising at least one fastening lower former having two second fastening devices on either side of the longitudinal box in order to each connect a second fastening point of the tank or tanks to the fastening lower former or formers, the first fastening point and the second fastening point of a tank being capable of being comprised in a plane perpendicular to the axis Y and comprising the centre of gravity of said tank.