An openable window comprising: a window frame comprising elongated, preferably wooden or wooden core frame members (2',2",2"',2""), a sash comprising elongated, preferably wooden or wooden core sash members (1',1",1"',1""), said sash being pivotally hung to the window frame so that the sash can be rotated relative to the frame between a closed position and open positions, a bolt slidably and rotatably received in a cylinder, said bolt being provided at one end with an engagement head, said cylinder having a first end and an opposite second end, said cylinder being fixed in a through-going bore in one of the sash members (1',1",1"',1"") with said second end of the cylinder facing a frame member (2',2",2"',2"") when the sash is in said closed position, a keep secured to a first side of said frame member (2',2",2"',2"") at a position where a front side of the keep faces said second end of said cylinder when the sash is in said closed position, said front side of said keep being provided with a slot, said keep being provided with a recess behind said slot, and an anchoring member that connects the keep to a second side of said frame member (2',2",2"',2"") that opposes said first side of said frame member (2',2",2"',2""), said bolt being movable inside said cylinder between a retracted position wherein said bolt does not prevent movement of said sash and an extended locking position wherein said engagement head projects through said slot and into said recess when said bolt is in said extended position and when said sash is in said closed position, said bolt thereby preventing movement of said sash. a window frame comprising elongated, preferably wooden or wooden core frame members (2',2",2"',2""), a sash comprising elongated, preferably wooden or wooden core sash members (1',1",1"',1""), said sash being pivotally hung to the window frame so that the sash can be rotated relative to the frame between a closed position and open positions, a bolt slidably and rotatably received in a cylinder, said bolt being provided at one end with an engagement head, said cylinder having a first end and an opposite second end, said cylinder being fixed in a through-going bore in one of the sash members (1',1",1"',1"") with said second end of the cylinder facing a frame member (2',2",2"',2"") when the sash is in said closed position, a keep secured to a first side of said frame member (2',2",2"',2"") at a position where a front side of the keep faces said second end of said cylinder when the sash is in said closed position, said front side of said keep being provided with a slot, said keep being provided with a recess behind said slot, and an anchoring member that connects the keep to a second side of said frame member (2',2",2"',2"") that opposes said first side of said frame member (2',2",2"',2""), said bolt being movable inside said cylinder between a retracted position wherein said bolt does not prevent movement of said sash and an extended locking position wherein said engagement head projects through said slot and into said recess when said bolt is in said extended position and when said sash is in said closed position, said bolt thereby preventing movement of said sash.