diff --git a/dataext/lruMap.go b/dataext/lruMap.go
index 0016466..0f3d155 100644
--- a/dataext/lruMap.go
+++ b/dataext/lruMap.go
@@ -19,38 +19,38 @@ import (
 // There are also a bunch of unit tests to ensure that the cache is always in a consistent state
 //
 
-type LRUMap[TData any] struct {
+type LRUMap[TKey comparable, TData any] struct {
 	maxsize int
 	lock    sync.Mutex
 
-	cache map[string]*cacheNode[TData]
+	cache map[TKey]*cacheNode[TKey, TData]
 
-	lfuHead *cacheNode[TData]
-	lfuTail *cacheNode[TData]
+	lfuHead *cacheNode[TKey, TData]
+	lfuTail *cacheNode[TKey, TData]
 }
 
-type cacheNode[TData any] struct {
-	key    string
+type cacheNode[TKey comparable, TData any] struct {
+	key    TKey
 	data   TData
-	parent *cacheNode[TData]
-	child  *cacheNode[TData]
+	parent *cacheNode[TKey, TData]
+	child  *cacheNode[TKey, TData]
 }
 
-func NewLRUMap[TData any](size int) *LRUMap[TData] {
+func NewLRUMap[TKey comparable, TData any](size int) *LRUMap[TKey, TData] {
 	if size <= 2 && size != 0 {
 		panic("Size must be > 2  (or 0)")
 	}
 
-	return &LRUMap[TData]{
+	return &LRUMap[TKey, TData]{
 		maxsize: size,
 		lock:    sync.Mutex{},
-		cache:   make(map[string]*cacheNode[TData], size+1),
+		cache:   make(map[TKey]*cacheNode[TKey, TData], size+1),
 		lfuHead: nil,
 		lfuTail: nil,
 	}
 }
 
-func (c *LRUMap[TData]) Put(key string, value TData) {
+func (c *LRUMap[TKey, TData]) Put(key TKey, value TData) {
 	if c.maxsize == 0 {
 		return // cache disabled
 	}
@@ -68,7 +68,7 @@ func (c *LRUMap[TData]) Put(key string, value TData) {
 	}
 
 	// key does not exist: insert into map and add to top of LFU
-	node = &cacheNode[TData]{
+	node = &cacheNode[TKey, TData]{
 		key:    key,
 		data:   value,
 		parent: nil,
@@ -93,7 +93,7 @@ func (c *LRUMap[TData]) Put(key string, value TData) {
 	}
 }
 
-func (c *LRUMap[TData]) TryGet(key string) (TData, bool) {
+func (c *LRUMap[TKey, TData]) TryGet(key TKey) (TData, bool) {
 	if c.maxsize == 0 {
 		return *new(TData), false // cache disabled
 	}
@@ -109,7 +109,7 @@ func (c *LRUMap[TData]) TryGet(key string) (TData, bool) {
 	return val.data, ok
 }
 
-func (c *LRUMap[TData]) moveNodeToTop(node *cacheNode[TData]) {
+func (c *LRUMap[TKey, TData]) moveNodeToTop(node *cacheNode[TKey, TData]) {
 	// (only called in critical section !)
 
 	if c.lfuHead == node { // fast case
@@ -142,7 +142,7 @@ func (c *LRUMap[TData]) moveNodeToTop(node *cacheNode[TData]) {
 	}
 }
 
-func (c *LRUMap[TData]) Size() int {
+func (c *LRUMap[TKey, TData]) Size() int {
 	c.lock.Lock()
 	defer c.lock.Unlock()
 	return len(c.cache)