Apparatus and methods are described including a blood pump configured to be placed inside a body of subject. The blood pump includes an impeller, a frame disposed around the impeller, and a distal-tip portion disposed distally with respect to the frame. A duckbill valve is disposed entirely within a distal most 10 mm of the distal-tip portion. The duckbill valve defines a wide inlet and a narrow tip that defines a slit therethrough. The duckbill valve is proximally facing, such that the wide inlet faces a distal end of the distal-tip portion and such that the narrow tip faces away from the distal end of distal-tip portion. Other applications are also described.