diff --git a/EIPS/eip-1155.md b/EIPS/eip-1155.md
index 4f1bfb4cafa9b9..d724da1c290007 100644
--- a/EIPS/eip-1155.md
+++ b/EIPS/eip-1155.md
@@ -424,6 +424,7 @@ If the optional `ERC1155Metadata_URI` extension is included:
     - An implementation MAY emit the `URI` event during a mint operation but it is NOT mandatory. An observer MAY fetch the metadata uri at mint time from the `uri` function if it was not emitted.    
 * The `uri` function SHOULD be used to retrieve values if no event was emitted. 
 * The `uri` function MUST return the same value as the latest event for an `_id` if it was emitted.
+* The `uri` function MUST NOT be used to check for the existence of a token as it is possible for an implementation to return a valid string even if the token does not exist.
 
 ```solidity
 pragma solidity ^0.5.9;