A rotor blade (26, 28) for a turbomachine, the rotor blade (26, 28) comprising: a main body having a shank, an airfoil extending radially outwardly from the shank, and a platform, the platform comprising a leading edge face axially spaced apart from a trailing edge face, and the main body comprising a pressure side slash face circumferentially spaced apart from a suction side slash face; a slot defined within each of the pressure side slash face and the suction side slash face, wherein the slot of the pressure side slash face and the slot of the suction side slash face each comprises: an upstream end portion defining an end; and a main body portion extending from the upstream end portion, the rotor blade being characterised in that the main body portion comprising a leading edge segment defined along the leading edge face, a platform segment defined along the platform, and a trailing edge segment defined along the trailing edge face; the upstream end portion tapering from the end to the leading edge segment of the main body portion, the upstream end portion comprising a retention wall that covers a portion of the end and defines an opening that is arranged to slidably receive at least a portion of a seal into the slot; the retention wall comprising an inner retention surface, the retention wall defining an offset (150, 152) from the opening. a main body having a shank, an airfoil extending radially outwardly from the shank, and a platform, the platform comprising a leading edge face axially spaced apart from a trailing edge face, and the main body comprising a pressure side slash face circumferentially spaced apart from a suction side slash face; a slot defined within each of the pressure side slash face and the suction side slash face, wherein the slot of the pressure side slash face and the slot of the suction side slash face each comprises: an upstream end portion defining an end; and a main body portion extending from the upstream end portion, the rotor blade being characterised in that the main body portion comprising a leading edge segment defined along the leading edge face, a platform segment defined along the platform, and a trailing edge segment defined along the trailing edge face; the upstream end portion tapering from the end to the leading edge segment of the main body portion, the upstream end portion comprising a retention wall that covers a portion of the end and defines an opening that is arranged to slidably receive at least a portion of a seal into the slot; the retention wall comprising an inner retention surface, the retention wall defining an offset (150, 152) from the opening. an upstream end portion defining an end; and a main body portion extending from the upstream end portion, the rotor blade being characterised in that the main body portion comprising a leading edge segment defined along the leading edge face, a platform segment defined along the platform, and a trailing edge segment defined along the trailing edge face; the upstream end portion tapering from the end to the leading edge segment of the main body portion, the upstream end portion comprising a retention wall that covers a portion of the end and defines an opening that is arranged to slidably receive at least a portion of a seal into the slot; the retention wall comprising an inner retention surface, the retention wall defining an offset (150, 152) from the opening.