diff --git a/man2/semop.2 b/man2/semop.2
index 245465c4c..b3b1bfc91 100644
--- a/man2/semop.2
+++ b/man2/semop.2
@@ -290,6 +290,9 @@ time specified by the
 structure whose address is passed in the
 .I timeout
 argument.
+(This sleep interval will be rounded up to the system clock granularity,
+and kernel scheduling delays mean that the interval
+may overrun by a small amount.)
 If the specified time limit has been reached,
 .BR semtimedop ()
 fails with