A modular safety ladder comprising a number of rungs connecting a first and a second guide rail (10, 110, 20, 120), and an upper ladder module and a lower ladder module, said modular safety ladder being able to be arranged in an un-assembled configuration, in which said upper ladder module is un-attached to said lower ladder module, and an assembled configuration, in which said upper ladder module is attached to said lower ladder module, wherein each ladder module (100, 700) comprises a first and a second guide rail portion (10, 110, 20, 120), and a rung connecting the first and second guide rail portions (10, 110, 20, 120), and a tightening device which in the assembled configuration upon activation pulls said ladder modules (100, 700) towards each other, characterized in that the modular safety ladder further comprises a spacer (200, 210, 220, 230, 240), the spacer in the assembled configuration being positioned to space apart the first guide rail portion (10, 110) of the upper ladder module from the first guide rail portion (10, 110) of the lower ladder module, wherein a collar part (217, 247) of the spacer (200, 210, 220, 230, 240) in the assembled configuration is positioned between a surface of the first guide rail portion (10, 110) of the upper ladder module and an opposite surface of the first guide rail portion (10, 110) of the lower ladder module so that tightening of the tightening device will squeeze or pinch or compress said collar part (217, 247) of the spacer between said surfaces, the spacer (210, 220, 230, 240) comprising an upper protrusion, wherein at least a part of the upper protrusion is arranged in a first support member channel (113, 127) of the upper ladder module when the modular safety ladder is arranged in the assembled configuration, the spacer comprising a lower protrusion, wherein at least a part of the lower protrusion is arranged in a first support member channel of the lower ladder module when the modular safety ladder is arranged in the assembled configuration, and the spacer comprising the collar part, said lower and upper protrusions (243, 245) extending in opposite directions away from said collar part. a number of rungs connecting a first and a second guide rail (10, 110, 20, 120), and an upper ladder module and a lower ladder module, said modular safety ladder being able to be arranged in an un-assembled configuration, in which said upper ladder module is un-attached to said lower ladder module, and an assembled configuration, in which said upper ladder module is attached to said lower ladder module, wherein each ladder module (100, 700) comprises a first and a second guide rail portion (10, 110, 20, 120), and a rung connecting the first and second guide rail portions (10, 110, 20, 120), and a tightening device which in the assembled configuration upon activation pulls said ladder modules (100, 700) towards each other, characterized in that the modular safety ladder further comprises a spacer (200, 210, 220, 230, 240), the spacer in the assembled configuration being positioned to space apart the first guide rail portion (10, 110) of the upper ladder module from the first guide rail portion (10, 110) of the lower ladder module, wherein a collar part (217, 247) of the spacer (200, 210, 220, 230, 240) in the assembled configuration is positioned between a surface of the first guide rail portion (10, 110) of the upper ladder module and an opposite surface of the first guide rail portion (10, 110) of the lower ladder module so that tightening of the tightening device will squeeze or pinch or compress said collar part (217, 247) of the spacer between said surfaces, the spacer (210, 220, 230, 240) comprising an upper protrusion, wherein at least a part of the upper protrusion is arranged in a first support member channel (113, 127) of the upper ladder module when the modular safety ladder is arranged in the assembled configuration, the spacer comprising a lower protrusion, wherein at least a part of the lower protrusion is arranged in a first support member channel of the lower ladder module when the modular safety ladder is arranged in the assembled configuration, and the spacer comprising the collar part, said lower and upper protrusions (243, 245) extending in opposite directions away from said collar part.