diff --git a/lib/rules/no-assignment-of-untracked-properties-used-in-tracking-contexts.js b/lib/rules/no-assignment-of-untracked-properties-used-in-tracking-contexts.js
index f60056936e..3121594f06 100644
--- a/lib/rules/no-assignment-of-untracked-properties-used-in-tracking-contexts.js
+++ b/lib/rules/no-assignment-of-untracked-properties-used-in-tracking-contexts.js
@@ -137,6 +137,7 @@ module.exports = {
                             minimum: 1,
                           },
                         },
+                        additionalProperties: false,
                       },
                       objects: {
                         type: 'object',
diff --git a/lib/rules/no-side-effects.js b/lib/rules/no-side-effects.js
index 014365598a..26209e670f 100644
--- a/lib/rules/no-side-effects.js
+++ b/lib/rules/no-side-effects.js
@@ -164,6 +164,7 @@ module.exports = {
               'Whether the rule should check plain (non-computed) getters in native classes for side effects.',
           },
         },
+        additionalProperties: false,
       },
     ],
   },