diff --git a/lib/aiken-content-ownership/validators/content_registry.ak b/lib/aiken-content-ownership/validators/content_registry.ak
index 0a785fe..64207ff 100644
--- a/lib/aiken-content-ownership/validators/content_registry.ak
+++ b/lib/aiken-content-ownership/validators/content_registry.ak
@@ -14,19 +14,37 @@ use aiken_content_ownership/types.{
   OwnershipRegistryDatum, StopContentRegistry, UpdateContent,
 }
 
+pub fn update_content_registry_at(
+  registry: List<ByteArray>,
+  index: Int,
+  new_value: ByteArray,
+) -> List<ByteArray> {
+  let spanned_registry = list.span(registry, index)
+  expect Some(dropped_head_tail) = list.tail(spanned_registry.2nd)
+  let updated_tail = list.push(dropped_head_tail, new_value)
+  list.concat(spanned_registry.1st, updated_tail)
+}
+
 pub fn check_is_content_registry_updated(
   old_datum: Datum,
   new_datum: Datum,
+  content_number: Int,
   new_content_hash: ByteArray,
 ) -> Bool {
   expect InlineDatum(raw_input_datum) = old_datum
   expect input_datum: ContentRegistryDatum = raw_input_datum
   expect InlineDatum(raw_output_datum) = new_datum
   expect output_datum: ContentRegistryDatum = raw_output_datum
+  let updated_registry =
+    update_content_registry_at(
+      input_datum.registry,
+      content_number,
+      new_content_hash,
+    )
   let is_content_registry_updated =
     output_datum == ContentRegistryDatum {
       count: input_datum.count,
-      registry: list.concat(input_datum.registry, [new_content_hash]),
+      registry: updated_registry,
     }
   is_content_registry_updated
 }
@@ -167,6 +185,7 @@ pub fn content_registry_logic(
             check_is_content_registry_updated(
               content_input.output.datum,
               content_output.datum,
+              content_number,
               new_content_hash,
             )
           expect InlineDatum(raw_ownership_ref_datum) =
diff --git a/lib/aiken-content-ownership/validators/ownership_registry.ak b/lib/aiken-content-ownership/validators/ownership_registry.ak
index 215cda1..1138477 100644
--- a/lib/aiken-content-ownership/validators/ownership_registry.ak
+++ b/lib/aiken-content-ownership/validators/ownership_registry.ak
@@ -4,7 +4,7 @@ use aiken/transaction.{
   InlineDatum, ScriptContext, ScriptPurpose, Spend, Transaction,
 }
 use aiken/transaction/value.{
-  PolicyId, flatten, from_minted_value, negate, without_lovelace,
+  AssetName, PolicyId, flatten, from_minted_value, negate, without_lovelace,
 }
 use aiken_content_ownership/common.{
   inputs_at, inputs_at_with_policy, inputs_token_quantity, inputs_with,
@@ -16,6 +16,17 @@ use aiken_content_ownership/types.{
   TransferOwnership,
 }
 
+pub fn update_ownership_registry_at(
+  registry: List<(PolicyId, AssetName)>,
+  index: Int,
+  new_value: (PolicyId, AssetName),
+) -> List<(PolicyId, AssetName)> {
+  let spanned_registry = list.span(registry, index)
+  expect Some(dropped_head_tail) = list.tail(spanned_registry.2nd)
+  let updated_tail = list.push(dropped_head_tail, new_value)
+  list.concat(spanned_registry.1st, updated_tail)
+}
+
 pub fn ownership_registry_logic(
   oracle_nft: PolicyId,
   _datum: OwnershipRegistryDatum,
@@ -85,7 +96,11 @@ pub fn ownership_registry_logic(
               let is_registry_updated =
                 output_datum == OwnershipRegistryDatum {
                   count: input_datum.count,
-                  registry: list.concat(input_datum.registry, [new_owner_token]),
+                  registry: update_ownership_registry_at(
+                    input_datum.registry,
+                    content_number,
+                    new_owner_token,
+                  ),
                 }
               let is_registry_value_clean =
                 list.length(flatten(ownership_output.value)) == 2
diff --git a/validators/tests/integration-tests/update_content.ak b/validators/tests/integration-tests/update_content.ak
index e69de29..8b13789 100644
--- a/validators/tests/integration-tests/update_content.ak
+++ b/validators/tests/integration-tests/update_content.ak
@@ -0,0 +1 @@
+
diff --git a/validators/tests/unit-tests/content_registry.ak b/validators/tests/unit-tests/content_registry.ak
index 879844d..53703be 100644
--- a/validators/tests/unit-tests/content_registry.ak
+++ b/validators/tests/unit-tests/content_registry.ak
@@ -16,7 +16,9 @@ use aiken_content_ownership/types.{
   StopContentRegistry, UpdateContent,
 }
 use aiken_content_ownership/utils.{get_registry_token_name}
-use aiken_content_ownership/validators/content_registry.{content_registry_logic}
+use aiken_content_ownership/validators/content_registry.{
+  content_registry_logic, update_content_registry_at,
+}
 
 type TestCase {
   is_content_count_updated: Bool,
@@ -242,6 +244,7 @@ type UpdateTestCase {
 }
 
 fn make_mock_tx_body_for_update(
+  record_count: Int,
   content_registry: List<ByteArray>,
   ownership_registry: List<(PolicyId, AssetName)>,
   owner: (PolicyId, AssetName),
@@ -291,7 +294,11 @@ fn make_mock_tx_body_for_update(
           ContentRegistryDatum {
             count: 6,
             registry: if test_case.is_registry_updated {
-              list.concat(content_registry, [new_content_hash])
+              update_content_registry_at(
+                content_registry,
+                record_count,
+                new_content_hash,
+              )
             } else {
               content_registry
             },
@@ -349,6 +356,7 @@ fn update_base_case(test_case: UpdateTestCase) {
   let dat = ContentRegistryDatum { count: 0, registry: current_registry }
   let tx =
     make_mock_tx_body_for_update(
+      4,
       current_registry,
       ownership_registry,
       owner,
diff --git a/validators/tests/unit-tests/ownership_registry.ak b/validators/tests/unit-tests/ownership_registry.ak
index b277e38..cb96ba4 100644
--- a/validators/tests/unit-tests/ownership_registry.ak
+++ b/validators/tests/unit-tests/ownership_registry.ak
@@ -19,7 +19,7 @@ use aiken_content_ownership/types.{
 }
 use aiken_content_ownership/utils.{get_registry_token_name}
 use aiken_content_ownership/validators/ownership_registry.{
-  ownership_registry_logic,
+  ownership_registry_logic, update_ownership_registry_at,
 }
 
 type CreateTestCase {
@@ -252,7 +252,11 @@ fn make_mock_tx_body_for_update(
           OwnershipRegistryDatum {
             count: record_count,
             registry: if test_case.is_registry_updated {
-              list.concat(ownership_registry, [new_owner])
+              update_ownership_registry_at(
+                ownership_registry,
+                record_count,
+                new_owner,
+              )
             } else {
               ownership_registry
             },