diff --git a/usr.bin/diff/pr.h b/usr.bin/diff/pr.h
index 80f20ca7c32..b2ff7e5d679 100644
--- a/usr.bin/diff/pr.h
+++ b/usr.bin/diff/pr.h
@@ -24,8 +24,6 @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <sys/event.h>
-
 struct pr {
 	int ostdout;
 	int pidfd;