diff --git a/lib/libc/sys/ktrace.2 b/lib/libc/sys/ktrace.2
index fe69d7e648f..97069e491f9 100644
--- a/lib/libc/sys/ktrace.2
+++ b/lib/libc/sys/ktrace.2
@@ -145,7 +145,7 @@ The following
 tunables influence the behaviour of
 .Fn ktrace :
 .Bl -tag -width indent
-.It Va kern.ktrace.geniosize
+.It Va kern.ktrace.genio_size
 bounds the amount of data a traced I/O request will log
 to the trace file.
 .It Va kern.ktrace.request_pool