diff --git a/near-plugins-derive/src/upgradable.rs b/near-plugins-derive/src/upgradable.rs
index b46bd65..86cc0a1 100644
--- a/near-plugins-derive/src/upgradable.rs
+++ b/near-plugins-derive/src/upgradable.rs
@@ -165,25 +165,30 @@ pub fn derive_upgradable(input: TokenStream) -> TokenStream {
             }
 
             #[#cratename::access_control_any(roles(#(#acl_roles_code_stagers),*))]
-            fn up_stage_code(&mut self, #[serializer(borsh)] code: Vec<u8>) {
+            fn up_stage_code(&mut self) {
+                let code = ::near_sdk::env::input().unwrap_or_default();
+
                 if code.is_empty() {
                     ::near_sdk::env::storage_remove(self.up_storage_key(__UpgradableStorageKey::Code).as_ref());
                     ::near_sdk::env::storage_remove(self.up_storage_key(__UpgradableStorageKey::StagingTimestamp).as_ref());
                 } else {
-                    let timestamp = ::near_sdk::env::block_timestamp() + self.up_get_duration(__UpgradableStorageKey::StagingDuration).unwrap_or(0);
+                    // Use saturating_add to prevent overflow
+                    let duration = self.up_get_duration(__UpgradableStorageKey::StagingDuration).unwrap_or(0);
+                    let timestamp = ::near_sdk::env::block_timestamp().saturating_add(duration);
+
+                    // Store the new code and timestamp
                     self.up_storage_write(__UpgradableStorageKey::Code, &code);
                     self.up_set_timestamp(__UpgradableStorageKey::StagingTimestamp, timestamp);
                 }
             }
-
             #[result_serializer(borsh)]
             fn up_staged_code(&self) -> Option<Vec<u8>> {
                 ::near_sdk::env::storage_read(self.up_storage_key(__UpgradableStorageKey::Code).as_ref())
             }
 
-            fn up_staged_code_hash(&self) -> Option<::near_sdk::CryptoHash> {
+            fn up_staged_code_hash(&self) -> Option<String> {
                 self.up_staged_code()
-                    .map(|code| Self::up_hash_code(code.as_ref()))
+                    .map(|code| ::near_sdk::bs58::encode(Self::up_hash_code(code.as_ref())).into_string())
             }
 
             #[#cratename::access_control_any(roles(#(#acl_roles_code_deployers),*))]
@@ -202,7 +207,7 @@ pub fn derive_upgradable(input: TokenStream) -> TokenStream {
                 }
 
                 let code = self.up_staged_code().unwrap_or_else(|| ::near_sdk::env::panic_str("Upgradable: No staged code"));
-                let expected_hash = ::near_sdk::base64::encode(Self::up_hash_code(code.as_ref()));
+                let expected_hash = ::near_sdk::bs58::encode(Self::up_hash_code(code.as_ref())).into_string();
                 if hash != expected_hash {
                     near_sdk::env::panic_str(
                         format!(
diff --git a/near-plugins-derive/tests/common/upgradable_contract.rs b/near-plugins-derive/tests/common/upgradable_contract.rs
index 6d1e239..e18ae65 100644
--- a/near-plugins-derive/tests/common/upgradable_contract.rs
+++ b/near-plugins-derive/tests/common/upgradable_contract.rs
@@ -1,7 +1,6 @@
 use near_plugins::upgradable::{FunctionCallArgs, UpgradableDurationStatus};
 
 use near_sdk::serde_json::json;
-use near_sdk::CryptoHash;
 use near_sdk::Duration;
 use near_workspaces::result::ExecutionFinalResult;
 use near_workspaces::{Account, Contract};
@@ -39,7 +38,7 @@ impl UpgradableContract {
     ) -> near_workspaces::Result<ExecutionFinalResult> {
         caller
             .call(self.contract.id(), "up_stage_code")
-            .args_borsh(code)
+            .args(code)
             .max_gas()
             .transact()
             .await
@@ -54,16 +53,13 @@ impl UpgradableContract {
         Ok(res.borsh::<Option<Vec<u8>>>()?)
     }
 
-    pub async fn up_staged_code_hash(
-        &self,
-        caller: &Account,
-    ) -> anyhow::Result<Option<CryptoHash>> {
+    pub async fn up_staged_code_hash(&self, caller: &Account) -> anyhow::Result<Option<String>> {
         let res = caller
             .call(self.contract.id(), "up_staged_code_hash")
             .max_gas()
             .transact()
             .await?;
-        Ok(res.json::<Option<CryptoHash>>()?)
+        Ok(res.json::<Option<String>>()?)
     }
 
     /// The `Promise` returned by trait method `up_deploy_code` is resolved in the `near_workspaces`
diff --git a/near-plugins-derive/tests/upgradable.rs b/near-plugins-derive/tests/upgradable.rs
index 34da63d..a8b9936 100644
--- a/near-plugins-derive/tests/upgradable.rs
+++ b/near-plugins-derive/tests/upgradable.rs
@@ -12,7 +12,7 @@ use common::utils::{
 };
 use near_plugins::upgradable::FunctionCallArgs;
 use near_sdk::serde_json::json;
-use near_sdk::{CryptoHash, Duration, Gas, NearToken, Timestamp};
+use near_sdk::{Duration, Gas, NearToken, Timestamp};
 use near_workspaces::network::Sandbox;
 use near_workspaces::result::ExecutionFinalResult;
 use near_workspaces::{Account, AccountId, Contract, Worker};
@@ -203,19 +203,17 @@ impl Setup {
     }
 }
 
-/// Panics if the conversion fails.
-fn convert_code_to_crypto_hash(code: &[u8]) -> CryptoHash {
-    near_sdk::env::sha256(code)
-        .try_into()
-        .expect("Code should be converted to CryptoHash")
+/// Converts code to a base58-encoded CryptoHash string.
+fn convert_code_to_crypto_hash(code: &[u8]) -> String {
+    let hash = near_sdk::env::sha256(code);
+    near_sdk::bs58::encode(hash).into_string()
 }
 
 /// Computes the hash `code` according the to requirements of the `hash` parameter of
 /// `Upgradable::up_deploy_code`.
 fn convert_code_to_deploy_hash(code: &[u8]) -> String {
-    use near_sdk::base64::Engine;
     let hash = near_sdk::env::sha256(code);
-    near_sdk::base64::prelude::BASE64_STANDARD.encode(hash)
+    near_sdk::bs58::encode(hash).into_string()
 }
 
 /// Smoke test of contract setup.
@@ -722,7 +720,7 @@ async fn test_deploy_code_in_batch_transaction_pitfall() -> anyhow::Result<()> {
     } }))
         .gas(Gas::from_tgas(220));
     let fn_call_remove_code = near_workspaces::operations::Function::new("up_stage_code")
-        .args_borsh(Vec::<u8>::new())
+        .args(Vec::<u8>::new())
         .gas(Gas::from_tgas(80));
 
     let res = dao
diff --git a/near-plugins/src/upgradable.rs b/near-plugins/src/upgradable.rs
index 2cca948..e03a807 100644
--- a/near-plugins/src/upgradable.rs
+++ b/near-plugins/src/upgradable.rs
@@ -91,13 +91,13 @@ pub trait Upgradable {
     /// specified via the `code_stagers` field of the `Upgradable` macro's `access_control_roles`
     /// attribute. The example contract (accessible via the `README`) shows how access control roles
     /// can be defined and passed on to the `Upgradable` macro.
-    fn up_stage_code(&mut self, code: Vec<u8>);
+    fn up_stage_code(&mut self);
 
     /// Returns the staged code.
     fn up_staged_code(&self) -> Option<Vec<u8>>;
 
     /// Returns the hash of the staged code
-    fn up_staged_code_hash(&self) -> Option<CryptoHash>;
+    fn up_staged_code_hash(&self) -> Option<String>;
 
     /// Allows an authorized account to deploy the staged code. It panics if no code is staged.
     ///
@@ -106,10 +106,8 @@ pub trait Upgradable {
     /// Some workflows (e.g. when a DAO interacts with an `Upgradable` contract) are facilitated if
     /// deployment succeeds only in case the hash of staged code corresponds to a given hash. This
     /// behavior can be enabled with the `hash` parameter. In case it is `h`, the deployment
-    /// succeeds only if `h` equals the base64 encoded string of the staged code's `sha256` hash. In
-    /// particular, the encoding according to [`near_sdk::base64::encode`] is expected. Note that
-    /// `near_sdk` uses a rather dated version of the `base64` crate whose API differs from current
-    /// versions.
+    /// succeeds only if `h` equals the bs58 encoded string of the staged code's `sha256` hash. In
+    /// particular, the encoding according to [`near_sdk::bs58::encode`] is expected.
     ///
     ///
     /// # Attaching a function call