diff --git a/doc/api/cli.md b/doc/api/cli.md
index 7b132e70132..52df262ec8c 100644
--- a/doc/api/cli.md
+++ b/doc/api/cli.md
@@ -3450,8 +3450,10 @@ reason any of these APIs takes a long time, other (seemingly unrelated) APIs
 that run in libuv's threadpool will experience degraded performance. In order to
 mitigate this issue, one potential solution is to increase the size of libuv's
 threadpool by setting the `'UV_THREADPOOL_SIZE'` environment variable to a value
-greater than `4` (its current default value). For more information, see the
-[libuv threadpool documentation][].
+greater than `4` (its current default value). However, setting this from inside
+the process using `process.env.UV_THREADPOOL_SIZE=size` is not guranteed to work
+as the threadpool would have been created as part of the runtime initialisation
+much before user code is run. For more information, see the [libuv threadpool documentation][].
 
 ## Useful V8 options