diff --git a/lib/libc/sys/select.2 b/lib/libc/sys/select.2
index 344adb141e7..528645c3184 100644
--- a/lib/libc/sys/select.2
+++ b/lib/libc/sys/select.2
@@ -57,6 +57,8 @@ and
 to see if some of their descriptors
 are ready for reading, are ready for writing, or have an exceptional
 condition pending, respectively.
+The only exceptional condition detectable is out-of-band
+data received on a socket.
 The first
 .Fa nfds
 descriptors are checked in each set;