diff --git a/nebulosa-image-format/src/main/kotlin/nebulosa/image/format/AbstractHeader.kt b/nebulosa-image-format/src/main/kotlin/nebulosa/image/format/AbstractHeader.kt
index 8fdb541a9..2181ae75a 100644
--- a/nebulosa-image-format/src/main/kotlin/nebulosa/image/format/AbstractHeader.kt
+++ b/nebulosa-image-format/src/main/kotlin/nebulosa/image/format/AbstractHeader.kt
@@ -3,8 +3,7 @@ package nebulosa.image.format
 import java.io.Serializable
 import java.util.*
 
-abstract class AbstractHeader protected constructor(@JvmField protected val cards: LinkedList<HeaderCard>) :
-    Header, MutableCollection<HeaderCard> by cards, Serializable {
+abstract class AbstractHeader protected constructor(@JvmField protected val cards: LinkedList<HeaderCard>) : Header, Serializable {
 
     constructor() : this(LinkedList<HeaderCard>())
 
@@ -27,6 +26,41 @@ abstract class AbstractHeader protected constructor(@JvmField protected val card
         }
     }
 
+    override val size
+        get() = cards.size
+
+    override fun contains(element: HeaderCard): Boolean {
+        return element in cards
+    }
+
+    override fun containsAll(elements: Collection<HeaderCard>): Boolean {
+        return cards.containsAll(elements)
+    }
+
+    override fun isEmpty(): Boolean {
+        return cards.isEmpty()
+    }
+
+    override fun iterator(): MutableIterator<HeaderCard> {
+        return cards.iterator()
+    }
+
+    override fun clear() {
+        cards.clear()
+    }
+
+    override fun remove(element: HeaderCard): Boolean {
+        return cards.remove(element)
+    }
+
+    override fun removeAll(elements: Collection<HeaderCard>): Boolean {
+        return cards.removeAll(elements.toSet())
+    }
+
+    override fun retainAll(elements: Collection<HeaderCard>): Boolean {
+        return cards.retainAll(elements.toSet())
+    }
+
     override fun delete(key: String): Boolean {
         return cards.removeIf { it.key == key }
     }
diff --git a/nebulosa-image-format/src/main/kotlin/nebulosa/image/format/WritableHeader.kt b/nebulosa-image-format/src/main/kotlin/nebulosa/image/format/WritableHeader.kt
index 4a6f4c017..abcc50f2b 100644
--- a/nebulosa-image-format/src/main/kotlin/nebulosa/image/format/WritableHeader.kt
+++ b/nebulosa-image-format/src/main/kotlin/nebulosa/image/format/WritableHeader.kt
@@ -20,6 +20,8 @@ interface WritableHeader : MutableCollection<HeaderCard> {
 
     fun addAll(cards: Iterable<HeaderCard>) = cards.forEach(::add)
 
+    override fun addAll(elements: Collection<HeaderCard>) = elements.fold(false) { a, b -> add(b) || a }
+
     fun delete(key: HeaderKey) = delete(key.key)
 
     fun delete(key: String): Boolean