diff --git a/src/core/iomgr/pollset_posix.c b/src/core/iomgr/pollset_posix.c
index a38517908da..826c792990e 100644
--- a/src/core/iomgr/pollset_posix.c
+++ b/src/core/iomgr/pollset_posix.c
@@ -420,6 +420,8 @@ static int unary_poll_pollset_maybe_work(grpc_pollset *pollset,
 
   pfd[1].events = grpc_fd_begin_poll(fd, pollset, POLLIN, POLLOUT, &fd_watcher);
 
+  /* poll fd count (argument 2) is shortened by one if we have no events
+     to poll on - such that it only includes the kicker */
   r = poll(pfd, GPR_ARRAY_SIZE(pfd) - (pfd[1].events == 0), timeout);
   GRPC_TIMER_MARK(GRPC_PTAG_POLL_FINISHED, r);