Guide extension catheters and methods of manufacturing and using guide extension catheters are disclosed. An example guide extension catheter may include a distal sheath having a proximal opening, a distal opening, and a central lumen extending therebetween. The guide extension catheter may also include a proximal shaft having an outer diameter smaller than an outer diameter of the distal sheath, the proximal shaft including a distal opening. The guide extension catheter may also include a coupling member for securing the distal sheath to the proximal shaft. The coupling member may include a distal portion attached to the distal sheath and a proximal portion disposed within the distal opening of the proximal shaft.