diff --git a/lib/modification.js b/lib/modification.js
index 7148c87..8cf78f9 100644
--- a/lib/modification.js
+++ b/lib/modification.js
@@ -73,7 +73,7 @@ const _getDataWithAppliedTransitions = (data, req) => {
 const addDiffToCtx = async function (req) {
   // store diff in audit data structure at context
   const _audit = (req.context._audit ??= {})
-  if (!_audit.diffs) _audit.diffs = new Map()
+  if (!_audit.diffs) _audit.diffs = new WeakMap()
 
   // get diff
   let diff = (await req.diff()) || {}
@@ -184,7 +184,7 @@ const _calcModificationLogsHandler = async function (req, beforeWrite, that) {
   const modificationLogs = _getDataModificationLogs(req, that, _audit.diffs.get(mapKey), beforeWrite)
 
   // store modificationLogs in audit data structure at context
-  if (!_audit.modificationLogs) _audit.modificationLogs = new Map()
+  if (!_audit.modificationLogs) _audit.modificationLogs = new WeakMap()
   const existingLogs = _audit.modificationLogs.get(mapKey) || {}
   _audit.modificationLogs.set(mapKey, Object.assign(existingLogs, modificationLogs))
 
diff --git a/lib/utils.js b/lib/utils.js
index e8edbe0..da7b0ea 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -236,7 +236,7 @@ const getDataSubject = (entity, model) => {
 const _getDataSubjectsMap = req => {
   const mapKey = getMapKeyForCurrentRequest(req)
   const _audit = (req.context._audit ??= {})
-  if (!_audit.dataSubjects) _audit.dataSubjects = new Map()
+  if (!_audit.dataSubjects) _audit.dataSubjects = new WeakMap()
   if (!_audit.dataSubjects.has(mapKey)) _audit.dataSubjects.set(mapKey, new Map())
   return _audit.dataSubjects.get(mapKey)
 }