A perforating gun that has a detonator section in which a window is formed is assembled by: disposing a detonating cord in an inner bore of the perforating gun; fixing a clip to a detonator; gripping the clip with an installation tool; inserting the clip laterally through the window of the detonator section using the installation tool; and attaching the clip to the detonator cord by pressing the clip against the detonator cord using the installation tool. The clip has a planar base, an opening formed in the base for receiving the detonator, and a pair of prongs extending from the base, wherein each prong of the pair of prongs extends from an edge of the base and has a gripping end.