diff --git a/guide_for_contributing.md b/guide_for_contributing.md
index 77cc3352..2b84f95c 100644
--- a/guide_for_contributing.md
+++ b/guide_for_contributing.md
@@ -14,6 +14,8 @@ I like my code to be tidy, so it saves me time if yours is too. Here are a few g
 
 - Please comment your methods/fields/classes! Preferably using Javadoc, but for small/private methods one line comments are OK. I find it hard enough to remember what I wrote a method for if it isn't commented, let alone trying to work out what yours are for. That said, you should try to name the method/field/class so it's obvious what it is anyway.
 
+- Please use @Override when overriding any methods.
+
 - Follow naming conventions. BLOCK_CAPITALS for constants, CapitalisedWords for classes, camelCase for almost everything else.
 
 - This isn't code related, but when you submit a PR, please tell me what it does! You don't need much, just something like "Makes item X do X" or "Fixes #162". If you're resolving an issue, put "Fixes", "Closes" or "Resolves" and then the issue number and Github will close it automatically.