diff --git a/src/main/java/org/glavo/nbt/tag/ParentTag.java b/src/main/java/org/glavo/nbt/tag/ParentTag.java
index 9abc5b1..ccfad9d 100644
--- a/src/main/java/org/glavo/nbt/tag/ParentTag.java
+++ b/src/main/java/org/glavo/nbt/tag/ParentTag.java
@@ -95,7 +95,8 @@ final void ensureTagsCapacityForAdd() {
 
         int arrayEnd = Math.min(size, tags.length);
         if (index < arrayEnd - 1) {
-            System.arraycopy(tags, index + 1, tags, index, size - index);
+            System.arraycopy(tags, index + 1, tags, index, size - index - 1);
+            tags[arrayEnd - 1] = null;
         } else if (oldTag != null) {
             tags[index] = null;
         }
@@ -179,7 +180,7 @@ final void moveTagToLast(T tag) {
     /// If the `tag` is already a child of another tag, removes it from old parent and adds it to this tag.
     @Contract(value = "_ -> this", mutates = "this,param1")
     public abstract ParentTag<T> addTag(@Flow(targetIsContainer = true)
-                                T tag) throws IllegalArgumentException;
+                                        T tag) throws IllegalArgumentException;
 
     /// Adds all `tags` to this tag.
     ///
diff --git a/src/test/java/org/glavo/nbt/tag/ListTagTest.java b/src/test/java/org/glavo/nbt/tag/ListTagTest.java
index 79ddb02..00038c4 100644
--- a/src/test/java/org/glavo/nbt/tag/ListTagTest.java
+++ b/src/test/java/org/glavo/nbt/tag/ListTagTest.java
@@ -15,6 +15,7 @@
  */
 package org.glavo.nbt.tag;
 
+import org.glavo.nbt.internal.ArrayAccessor;
 import org.junit.jupiter.api.Test;
 
 import java.util.function.Supplier;
@@ -238,4 +239,49 @@ void testCloneEqualsAndIndependentChildren() {
         assertEquals("changed", cloneFirst.get());
         assertContentNotEquals(tag, clone);
     }
+
+    @Test
+    void testRemoveAt() {
+        ListTag<IntTag> list = new ListTag<>();
+        for (int i = 0; i < 9; i++) {
+            list.addTag(new IntTag(i));
+        }
+        assertEquals(new IntTag(6), list.removeTagAt(6));
+        assertEquals(8, list.size());
+        assertArrayEquals(new IntTag[]{
+                new IntTag(0), new IntTag(1), new IntTag(2),
+                new IntTag(3), new IntTag(4), new IntTag(5),
+                new IntTag(7), new IntTag(8), null,
+                null, null, null}, list.tags);
+    }
+
+    @Test
+    void testRemoveAtCapacity() {
+        ListTag<IntTag> list = new ListTag<>();
+        for (int i = 0; i < ArrayAccessor.DEFAULT_CAPACITY; i++) {
+            list.addTag(new IntTag(i));
+        }
+        assertEquals(new IntTag(6), list.removeTagAt(6));
+        assertEquals(ArrayAccessor.DEFAULT_CAPACITY - 1, list.size());
+        assertArrayEquals(new IntTag[]{
+                new IntTag(0), new IntTag(1), new IntTag(2),
+                new IntTag(3), new IntTag(4), new IntTag(5),
+                new IntTag(7), new IntTag(8), new IntTag(9),
+                new IntTag(10), new IntTag(11), null}, list.tags);
+    }
+
+    @Test
+    void testRemoveAtEnd() {
+        ListTag<IntTag> list = new ListTag<>();
+        for (int i = 0; i < ArrayAccessor.DEFAULT_CAPACITY; i++) {
+            list.addTag(new IntTag(i));
+        }
+        assertEquals(new IntTag(11), list.removeTagAt(11));
+        assertEquals(ArrayAccessor.DEFAULT_CAPACITY - 1, list.size());
+        assertArrayEquals(new IntTag[]{
+                new IntTag(0), new IntTag(1), new IntTag(2),
+                new IntTag(3), new IntTag(4), new IntTag(5),
+                new IntTag(6), new IntTag(7), new IntTag(8),
+                new IntTag(9), new IntTag(10), null}, list.tags);
+    }
 }