diff --git a/lib/libsys/aio_cancel.2 b/lib/libsys/aio_cancel.2
--- a/lib/libsys/aio_cancel.2
+++ b/lib/libsys/aio_cancel.2
@@ -80,6 +80,10 @@
 .Fa fildes
 argument
 is an invalid file descriptor.
+.It Bq Er ENOSYS
+The
+.Fn aio_cancel
+system call is not supported.
 .El
 .Sh SEE ALSO
 .Xr aio_error 2 ,
diff --git a/lib/libsys/aio_error.2 b/lib/libsys/aio_error.2
--- a/lib/libsys/aio_error.2
+++ b/lib/libsys/aio_error.2
@@ -72,6 +72,10 @@
 .Fa iocb
 argument
 does not reference an outstanding asynchronous I/O request.
+.It Bq Er ENOSYS
+The
+.Fn aio_error
+system call is not supported.
 .El
 .Sh SEE ALSO
 .Xr aio_cancel 2 ,
diff --git a/lib/libsys/aio_fsync.2 b/lib/libsys/aio_fsync.2
--- a/lib/libsys/aio_fsync.2
+++ b/lib/libsys/aio_fsync.2
@@ -97,6 +97,10 @@
 .Bl -tag -width Er
 .It Bq Er EAGAIN
 The request was not queued because of system resource limitations.
+.It Bq Er ENOSYS
+The
+.Fn aio_fsync
+system call is not supported.
 .It Bq Er EINVAL
 The asynchronous notification method in
 .Fa iocb->aio_sigevent.sigev_notify
diff --git a/lib/libsys/aio_return.2 b/lib/libsys/aio_return.2
--- a/lib/libsys/aio_return.2
+++ b/lib/libsys/aio_return.2
@@ -73,6 +73,10 @@
 .Fa iocb
 argument
 does not reference a completed asynchronous I/O request.
+.It Bq Er ENOSYS
+The
+.Fn aio_return
+system call is not supported.
 .It Bq Er EINVAL
 The I/O operation was submitted with
 .Fn lio_listio ,
diff --git a/lib/libsys/aio_suspend.2 b/lib/libsys/aio_suspend.2
--- a/lib/libsys/aio_suspend.2
+++ b/lib/libsys/aio_suspend.2
@@ -89,6 +89,10 @@
 variable, or at least one of the requests is not valid.
 .It Bq Er EINTR
 the suspend was interrupted by a signal.
+.It Bq Er ENOSYS
+The
+.Fn aio_suspend
+system call is not supported.
 .El
 .Sh SEE ALSO
 .Xr aio_cancel 2 ,
diff --git a/lib/libsys/aio_waitcomplete.2 b/lib/libsys/aio_waitcomplete.2
--- a/lib/libsys/aio_waitcomplete.2
+++ b/lib/libsys/aio_waitcomplete.2
@@ -105,6 +105,10 @@
 .It Bq Er EINPROGRESS
 The specified time limit expired before any asynchronous I/O requests
 completed.
+.It Bq Er ENOSYS
+The
+.Fn aio_waitcomplete
+system call is not supported.
 .El
 .Sh SEE ALSO
 .Xr aio_cancel 2 ,