diff --git a/vfs/vfs.md b/vfs/vfs.md
index 377a946b6..5288a969e 100644
--- a/vfs/vfs.md
+++ b/vfs/vfs.md
@@ -116,7 +116,8 @@ longest. This cache flushing strategy is efficient and more relevant
 files are likely to remain cached.
 
 The `--vfs-cache-max-age` will evict files from the cache
-after the set time since last access has passed. The default value of
+after the set time since last access has passed; it is based on access time,
+not on when the file was first added to the cache. The default value of
 1 hour will start evicting files from cache that haven't been accessed
 for 1 hour. When a cached file is accessed the 1 hour timer is reset to 0
 and will wait for 1 more hour before evicting. Specify the time with