diff --git a/modules/evm/src/bench/mock.rs b/modules/evm/src/bench/mock.rs
index 85f1744cdf..48ffe44054 100644
--- a/modules/evm/src/bench/mock.rs
+++ b/modules/evm/src/bench/mock.rs
@@ -139,6 +139,7 @@ parameter_types! {
 impl module_idle_scheduler::Config for Runtime {
 	type RuntimeEvent = RuntimeEvent;
 	type WeightInfo = ();
+	type Index = Nonce;
 	type Task = ScheduledTasks;
 	type MinimumWeightRemainInBlock = MinimumWeightRemainInBlock;
 	type RelayChainBlockNumberProvider = MockBlockNumberProvider;
diff --git a/modules/evm/src/lib.rs b/modules/evm/src/lib.rs
index 50eaadfbe7..71fd023eca 100644
--- a/modules/evm/src/lib.rs
+++ b/modules/evm/src/lib.rs
@@ -245,7 +245,7 @@ pub mod module {
 		type Task: DispatchableTask + FullCodec + Debug + Clone + PartialEq + TypeInfo + From<EvmTask<Self>>;
 
 		/// Idle scheduler for the evm task.
-		type IdleScheduler: IdleScheduler<Self::Task>;
+		type IdleScheduler: IdleScheduler<Nonce, Self::Task>;
 
 		/// Weight information for the extrinsics in this module.
 		type WeightInfo: WeightInfo;
@@ -259,13 +259,13 @@ pub mod module {
 	}
 
 	#[derive(Clone, Eq, PartialEq, RuntimeDebug, Encode, Decode, TypeInfo)]
-	pub struct AccountInfo<Index> {
-		pub nonce: Index,
+	pub struct AccountInfo<Nonce> {
+		pub nonce: Nonce,
 		pub contract_info: Option<ContractInfo>,
 	}
 
-	impl<Index> AccountInfo<Index> {
-		pub fn new(nonce: Index, contract_info: Option<ContractInfo>) -> Self {
+	impl<Nonce> AccountInfo<Nonce> {
+		pub fn new(nonce: Nonce, contract_info: Option<ContractInfo>) -> Self {
 			Self { nonce, contract_info }
 		}
 	}
@@ -278,9 +278,9 @@ pub mod module {
 
 	#[derive(Clone, Eq, PartialEq, Encode, Decode, RuntimeDebug, TypeInfo, Default, Serialize, Deserialize)]
 	/// Account definition used for genesis block construction.
-	pub struct GenesisAccount<Balance, Index> {
+	pub struct GenesisAccount<Balance, Nonce> {
 		/// Account nonce.
-		pub nonce: Index,
+		pub nonce: Nonce,
 		/// Account balance.
 		pub balance: Balance,
 		/// Full account storage.
@@ -432,8 +432,8 @@ pub mod module {
 					let out = runtime.machine().return_value();
 					<Pallet<T>>::create_contract(source, *address, true, out);
 
-					for (index, value) in &account.storage {
-						AccountStorages::<T>::insert(address, index, value);
+					for (nonce, value) in &account.storage {
+						AccountStorages::<T>::insert(address, nonce, value);
 					}
 				}
 			});
diff --git a/modules/evm/src/mock.rs b/modules/evm/src/mock.rs
index 9c1653de49..1a27dd39ae 100644
--- a/modules/evm/src/mock.rs
+++ b/modules/evm/src/mock.rs
@@ -130,6 +130,7 @@ parameter_types! {
 impl module_idle_scheduler::Config for Runtime {
 	type RuntimeEvent = RuntimeEvent;
 	type WeightInfo = ();
+	type Index = Nonce;
 	type Task = ScheduledTasks;
 	type MinimumWeightRemainInBlock = MinimumWeightRemainInBlock;
 	type RelayChainBlockNumberProvider = MockBlockNumberProvider;
diff --git a/modules/idle-scheduler/src/lib.rs b/modules/idle-scheduler/src/lib.rs
index 5c4b87641f..d373de69b9 100644
--- a/modules/idle-scheduler/src/lib.rs
+++ b/modules/idle-scheduler/src/lib.rs
@@ -28,10 +28,10 @@ use frame_support::pallet_prelude::*;
 use frame_system::pallet_prelude::*;
 pub use module_support::{DispatchableTask, IdleScheduler};
 use parity_scale_codec::FullCodec;
-use primitives::{task::TaskResult, BlockNumber, Nonce};
+use primitives::{task::TaskResult, BlockNumber};
 use scale_info::TypeInfo;
 use sp_runtime::{
-	traits::{BlockNumberProvider, One},
+	traits::{BlockNumberProvider, CheckedAdd, One},
 	ArithmeticError,
 };
 use sp_std::{cmp::PartialEq, fmt::Debug, prelude::*};
@@ -53,6 +53,9 @@ pub mod module {
 		/// Weight information for the extrinsics in this module.
 		type WeightInfo: WeightInfo;
 
+		/// The index of tasks.
+		type Index: Parameter + Default + One + CheckedAdd + Copy + TypeInfo;
+
 		/// Dispatchable tasks.
 		type Task: DispatchableTask + FullCodec + Debug + Clone + PartialEq + TypeInfo;
 
@@ -74,22 +77,22 @@ pub mod module {
 	#[pallet::generate_deposit(pub fn deposit_event)]
 	pub enum Event<T: Config> {
 		/// A task has been dispatched on_idle.
-		TaskDispatched { task_id: Nonce, result: DispatchResult },
+		TaskDispatched { task_id: T::Index, result: DispatchResult },
 		/// A task is added.
-		TaskAdded { task_id: Nonce, task: T::Task },
+		TaskAdded { task_id: T::Index, task: T::Task },
 	}
 
 	/// The schedule tasks waiting to dispatch. After task is dispatched, it's removed.
 	///
-	/// Tasks: map Nonce => Task
+	/// Tasks: map T::Index => Task
 	#[pallet::storage]
 	#[pallet::getter(fn tasks)]
-	pub type Tasks<T: Config> = StorageMap<_, Twox64Concat, Nonce, T::Task, OptionQuery>;
+	pub type Tasks<T: Config> = StorageMap<_, Twox64Concat, T::Index, T::Task, OptionQuery>;
 
 	/// The task id used to index tasks.
 	#[pallet::storage]
 	#[pallet::getter(fn next_task_id)]
-	pub type NextTaskId<T: Config> = StorageValue<_, Nonce, ValueQuery>;
+	pub type NextTaskId<T: Config> = StorageValue<_, T::Index, ValueQuery>;
 
 	/// A temporary variable used to check if should skip dispatch schedule task or not.
 	#[pallet::storage]
@@ -151,7 +154,7 @@ pub mod module {
 
 impl<T: Config> Pallet<T> {
 	/// Add the task to the queue to be dispatched later.
-	fn do_schedule_task(task: T::Task) -> Result<Nonce, DispatchError> {
+	fn do_schedule_task(task: T::Task) -> Result<T::Index, DispatchError> {
 		let id = Self::get_next_task_id()?;
 		Tasks::<T>::insert(id, &task);
 		Self::deposit_event(Event::<T>::TaskAdded { task_id: id, task });
@@ -159,10 +162,10 @@ impl<T: Config> Pallet<T> {
 	}
 
 	/// Retrieves the next task ID from storage, and increment it by one.
-	fn get_next_task_id() -> Result<Nonce, DispatchError> {
-		NextTaskId::<T>::mutate(|current| -> Result<Nonce, DispatchError> {
+	fn get_next_task_id() -> Result<T::Index, DispatchError> {
+		NextTaskId::<T>::mutate(|current| -> Result<T::Index, DispatchError> {
 			let id = *current;
-			*current = current.checked_add(One::one()).ok_or(ArithmeticError::Overflow)?;
+			*current = current.checked_add(&One::one()).ok_or(ArithmeticError::Overflow)?;
 			Ok(id)
 		})
 	}
@@ -175,7 +178,7 @@ impl<T: Config> Pallet<T> {
 			return total_weight;
 		}
 
-		let mut completed_tasks: Vec<(Nonce, TaskResult)> = vec![];
+		let mut completed_tasks: Vec<(T::Index, TaskResult)> = vec![];
 
 		for (id, task) in Tasks::<T>::iter() {
 			let result = task.dispatch(weight_remaining);
@@ -197,7 +200,7 @@ impl<T: Config> Pallet<T> {
 	}
 
 	/// Removes completed tasks and deposits events.
-	pub fn remove_completed_tasks(completed_tasks: Vec<(Nonce, TaskResult)>) {
+	pub fn remove_completed_tasks(completed_tasks: Vec<(T::Index, TaskResult)>) {
 		// Deposit event and remove completed tasks.
 		for (id, result) in completed_tasks {
 			Self::deposit_event(Event::<T>::TaskDispatched {
@@ -209,8 +212,8 @@ impl<T: Config> Pallet<T> {
 	}
 }
 
-impl<T: Config> IdleScheduler<T::Task> for Pallet<T> {
-	fn schedule(task: T::Task) -> Result<Nonce, DispatchError> {
+impl<T: Config> IdleScheduler<T::Index, T::Task> for Pallet<T> {
+	fn schedule(task: T::Task) -> Result<T::Index, DispatchError> {
 		Self::do_schedule_task(task)
 	}
 
@@ -218,7 +221,7 @@ impl<T: Config> IdleScheduler<T::Task> for Pallet<T> {
 	/// Otherwise the scheduler will keep the task and run it later.
 	/// NOTE: Only used for synchronous execution case, because `T::WeightInfo::clear_tasks()` is
 	/// not considered.
-	fn dispatch(id: Nonce, weight_limit: Weight) -> Weight {
+	fn dispatch(id: T::Index, weight_limit: Weight) -> Weight {
 		if let Some(task) = Tasks::<T>::get(id) {
 			let result = task.dispatch(weight_limit);
 			let used_weight = result.used_weight;
diff --git a/modules/idle-scheduler/src/mock.rs b/modules/idle-scheduler/src/mock.rs
index f3aa1e4e45..71ab1ae6ad 100644
--- a/modules/idle-scheduler/src/mock.rs
+++ b/modules/idle-scheduler/src/mock.rs
@@ -24,8 +24,7 @@ use crate as module_idle_scheduler;
 use frame_support::weights::Weight;
 use frame_support::{construct_runtime, derive_impl, parameter_types, traits::ConstU32};
 use module_support::DispatchableTask;
-use primitives::{define_combined_task, task::TaskResult};
-pub use sp_runtime::offchain::storage::StorageValueRef;
+use primitives::{define_combined_task, task::TaskResult, Nonce};
 use sp_runtime::BuildStorage;
 
 use super::*;
@@ -62,6 +61,7 @@ parameter_types! {
 impl module_idle_scheduler::Config for Runtime {
 	type RuntimeEvent = RuntimeEvent;
 	type WeightInfo = ();
+	type Index = Nonce;
 	type Task = ScheduledTasks;
 	type MinimumWeightRemainInBlock = MinimumWeightRemainInBlock;
 	type RelayChainBlockNumberProvider = MockBlockNumberProvider;
diff --git a/modules/support/src/lib.rs b/modules/support/src/lib.rs
index d2ca4f104a..7828a4f476 100644
--- a/modules/support/src/lib.rs
+++ b/modules/support/src/lib.rs
@@ -22,7 +22,7 @@
 #![allow(clippy::type_complexity)]
 
 use frame_support::pallet_prelude::{DispatchClass, Pays, Weight};
-use primitives::{task::TaskResult, Balance, CurrencyId, Multiplier, Nonce, ReserveIdentifier};
+use primitives::{task::TaskResult, Balance, CurrencyId, Multiplier, ReserveIdentifier};
 use sp_runtime::{
 	traits::CheckedDiv, transaction_validity::TransactionValidityError, DispatchError, DispatchResult, FixedU128,
 };
@@ -139,9 +139,9 @@ pub trait DispatchableTask {
 }
 
 /// Idle scheduler trait
-pub trait IdleScheduler<Task> {
-	fn schedule(task: Task) -> Result<Nonce, DispatchError>;
-	fn dispatch(id: Nonce, weight: Weight) -> Weight;
+pub trait IdleScheduler<Index, Task> {
+	fn schedule(task: Task) -> Result<Index, DispatchError>;
+	fn dispatch(id: Index, weight: Weight) -> Weight;
 }
 
 #[cfg(feature = "std")]
@@ -152,11 +152,11 @@ impl DispatchableTask for () {
 }
 
 #[cfg(feature = "std")]
-impl<Task> IdleScheduler<Task> for () {
-	fn schedule(_task: Task) -> Result<Nonce, DispatchError> {
+impl<Index, Task> IdleScheduler<Index, Task> for () {
+	fn schedule(_task: Task) -> Result<Index, DispatchError> {
 		unimplemented!()
 	}
-	fn dispatch(_id: Nonce, _weight: Weight) -> Weight {
+	fn dispatch(_id: Index, _weight: Weight) -> Weight {
 		unimplemented!()
 	}
 }
diff --git a/runtime/acala/src/lib.rs b/runtime/acala/src/lib.rs
index c5ce678594..dab6332264 100644
--- a/runtime/acala/src/lib.rs
+++ b/runtime/acala/src/lib.rs
@@ -1632,6 +1632,7 @@ parameter_types!(
 impl module_idle_scheduler::Config for Runtime {
 	type RuntimeEvent = RuntimeEvent;
 	type WeightInfo = ();
+	type Index = Nonce;
 	type Task = ScheduledTasks;
 	type MinimumWeightRemainInBlock = MinimumWeightRemainInBlock;
 	type RelayChainBlockNumberProvider = RelaychainDataProvider<Runtime>;
diff --git a/runtime/common/src/mock.rs b/runtime/common/src/mock.rs
index ec4f58a480..f750a913b4 100644
--- a/runtime/common/src/mock.rs
+++ b/runtime/common/src/mock.rs
@@ -28,7 +28,7 @@ use module_support::{mocks::MockAddressMapping, DispatchableTask};
 use orml_traits::parameter_type_with_key;
 use parity_scale_codec::{Decode, Encode};
 use primitives::{
-	define_combined_task, evm::convert_decimals_to_evm, task::TaskResult, Amount, BlockNumber, CurrencyId,
+	define_combined_task, evm::convert_decimals_to_evm, task::TaskResult, Amount, BlockNumber, CurrencyId, Nonce,
 	ReserveIdentifier, TokenSymbol,
 };
 use scale_info::TypeInfo;
@@ -136,6 +136,7 @@ parameter_types! {
 impl module_idle_scheduler::Config for TestRuntime {
 	type RuntimeEvent = RuntimeEvent;
 	type WeightInfo = ();
+	type Index = Nonce;
 	type Task = ScheduledTasks;
 	type MinimumWeightRemainInBlock = MinimumWeightRemainInBlock;
 	type RelayChainBlockNumberProvider = MockBlockNumberProvider;
diff --git a/runtime/common/src/precompile/mock.rs b/runtime/common/src/precompile/mock.rs
index d925889724..e82baf67c4 100644
--- a/runtime/common/src/precompile/mock.rs
+++ b/runtime/common/src/precompile/mock.rs
@@ -208,6 +208,7 @@ parameter_types! {
 impl module_idle_scheduler::Config for Test {
 	type RuntimeEvent = RuntimeEvent;
 	type WeightInfo = ();
+	type Index = Nonce;
 	type Task = ScheduledTasks;
 	type MinimumWeightRemainInBlock = MinimumWeightRemainInBlock;
 	type RelayChainBlockNumberProvider = MockBlockNumberProvider;
diff --git a/runtime/karura/src/lib.rs b/runtime/karura/src/lib.rs
index b36513aa51..3cc5ad92f7 100644
--- a/runtime/karura/src/lib.rs
+++ b/runtime/karura/src/lib.rs
@@ -1639,6 +1639,7 @@ parameter_types!(
 impl module_idle_scheduler::Config for Runtime {
 	type RuntimeEvent = RuntimeEvent;
 	type WeightInfo = ();
+	type Index = Nonce;
 	type Task = ScheduledTasks;
 	type MinimumWeightRemainInBlock = MinimumWeightRemainInBlock;
 	type RelayChainBlockNumberProvider = RelaychainDataProvider<Runtime>;
diff --git a/runtime/mandala/src/lib.rs b/runtime/mandala/src/lib.rs
index adf81885f7..83373d1d7e 100644
--- a/runtime/mandala/src/lib.rs
+++ b/runtime/mandala/src/lib.rs
@@ -1799,6 +1799,7 @@ parameter_types!(
 impl module_idle_scheduler::Config for Runtime {
 	type RuntimeEvent = RuntimeEvent;
 	type WeightInfo = weights::module_idle_scheduler::WeightInfo<Runtime>;
+	type Index = Nonce;
 	type Task = ScheduledTasks;
 	type MinimumWeightRemainInBlock = MinimumWeightRemainInBlock;
 	type RelayChainBlockNumberProvider = RelaychainDataProvider<Runtime>;