A door closer includes a body formed with a cylinder and a piston system located in the cylinder and functionally connectable to the door. The piston system divides the cylinder into a first cylinder volume on a first side of the piston system and a second cylinder volume on a second side of the piston system. A spring located in the second cylinder volume. A flow channel formed in the body guides flow of fluid from the first cylinder volume to the second cylinder volume, and a control valve for regulates rate of fluid flow through the flow channel. A filter is positioned across the flow channel upstream of the control valve relative to flow of fluid through the flow channel from the first cylinder volume to the second cylinder volume. The filter presents a filter area greater than the cross-sectional area of the flow channel to incoming flow to the filter and presents a filter area substantially equal to the cross-sectional area of the flow channel to outgoing flow from the filter.