diff --git a/ADBLOCKING.md b/ADBLOCKING.md
index 51346662..37509179 100644
--- a/ADBLOCKING.md
+++ b/ADBLOCKING.md
@@ -73,6 +73,7 @@ Apart from using a hosts file, you can block most in-app ads by blocking this ad
 
 You'll need to enable filtering and (temporarily) logging for this (you can do this by using the *Configure* button; check both options)
 and you'll need to wait until the address appears (you can speed this up by opening some apps with in-app ads).
+Note that ads are likely being cached, so this may not take effect immediately.
 
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