diff --git a/doc/hosting/environment-variables.md b/doc/hosting/environment-variables.md
index 731feb9..a5201cd 100644
--- a/doc/hosting/environment-variables.md
+++ b/doc/hosting/environment-variables.md
@@ -58,7 +58,9 @@ This setting specifies the hostname or IP address that PixivFE should listen on
 
 **Default:** `UTC`
 
-The time zone used for displaying dates and times throughout the application, including relative times (e.g., "2 hours ago") and full dates. The value should be a valid [tz database name](https://en.wikipedia.org/wiki/List_of_tz_database_time_zones).
+The time zone used for displaying dates and times throughout the application, including relative times (e.g., "2 hours ago") and full dates.
+
+The value must be a valid [tz database name](https://en.wikipedia.org/wiki/List_of_tz_database_time_zones) and match the geolocation of the IP address used for making requests to the Pixiv API, which returns dates in the client's local time. Setting the timezone ensures those dates are interpreted and displayed correctly in the application.
 
 Example:
 ```