diff --git a/lib/libc/sys/read.2 b/lib/libc/sys/read.2
--- a/lib/libc/sys/read.2
+++ b/lib/libc/sys/read.2
@@ -28,7 +28,7 @@
 .\"     @(#)read.2	8.4 (Berkeley) 2/26/94
 .\" $FreeBSD$
 .\"
-.Dd June 4, 2020
+.Dd October 7, 2022
 .Dt READ 2
 .Os
 .Sh NAME
@@ -250,6 +250,8 @@
 values in the
 .Fa iov
 array overflowed a 32-bit integer.
+.It Bq Er EINVAL
+The current file offset is not a multiple of the block size.
 .It Bq Er EFAULT
 Part of the
 .Fa iov
diff --git a/lib/libc/sys/write.2 b/lib/libc/sys/write.2
--- a/lib/libc/sys/write.2
+++ b/lib/libc/sys/write.2
@@ -28,7 +28,7 @@
 .\"     @(#)write.2	8.5 (Berkeley) 4/2/94
 .\" $FreeBSD$
 .\"
-.Dd February 11, 2021
+.Dd October 7, 2022
 .Dt WRITE 2
 .Os
 .Sh NAME
@@ -205,6 +205,8 @@
 if the sysctl
 .Va debug.iosize_max_clamp
 is non-zero).
+.It Bq Er EINVAL
+The current file offset is not a multiple of the block size.
 .It Bq Er EINTEGRITY
 The backing store for
 .Fa fd