Index: lib/libc/sys/read.2
===================================================================
--- lib/libc/sys/read.2
+++ lib/libc/sys/read.2
@@ -245,6 +245,8 @@
 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
Index: lib/libc/sys/write.2
===================================================================
--- lib/libc/sys/write.2
+++ lib/libc/sys/write.2
@@ -243,6 +243,8 @@
 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 ENOBUFS
 The mbuf pool has been completely exhausted when writing to a socket.
 .El