diff --git a/substrate/frame/support/src/error.rs b/substrate/frame/support/src/error.rs
index 79ffde539c..c0a886907d 100644
--- a/substrate/frame/support/src/error.rs
+++ b/substrate/frame/support/src/error.rs
@@ -77,7 +77,7 @@ macro_rules! decl_error {
 				$generic:ident: $trait:path
 				$(, $inst_generic:ident: $instance:path)?
 			>
-			$( where $( $where_ty:ty: $where_bound:path )* $(,)? )?
+			$( where $( $where_ty:ty: $where_bound:path ),* $(,)? )?
 		{
 			$(
 				$( #[doc = $doc_attr:tt] )*
@@ -88,7 +88,7 @@ macro_rules! decl_error {
 	) => {
 		$(#[$attr])*
 		pub enum $error<$generic: $trait $(, $inst_generic: $instance)?>
-		$( where $( $where_ty: $where_bound )* )?
+		$( where $( $where_ty: $where_bound ),* )?
 		{
 			#[doc(hidden)]
 			__Ignore(
@@ -103,7 +103,7 @@ macro_rules! decl_error {
 
 		impl<$generic: $trait $(, $inst_generic: $instance)?> $crate::sp_std::fmt::Debug
 			for $error<$generic $(, $inst_generic)?>
-		$( where $( $where_ty: $where_bound )* )?
+		$( where $( $where_ty: $where_bound ),* )?
 		{
 			fn fmt(&self, f: &mut $crate::sp_std::fmt::Formatter<'_>) -> $crate::sp_std::fmt::Result {
 				f.write_str(self.as_str())
@@ -111,7 +111,7 @@ macro_rules! decl_error {
 		}
 
 		impl<$generic: $trait $(, $inst_generic: $instance)?> $error<$generic $(, $inst_generic)?>
-		$( where $( $where_ty: $where_bound )* )?
+		$( where $( $where_ty: $where_bound ),* )?
 		{
 			fn as_u8(&self) -> u8 {
 				$crate::decl_error! {
@@ -136,7 +136,7 @@ macro_rules! decl_error {
 
 		impl<$generic: $trait $(, $inst_generic: $instance)?> From<$error<$generic $(, $inst_generic)?>>
 			for &'static str
-		$( where $( $where_ty: $where_bound )* )?
+		$( where $( $where_ty: $where_bound ),* )?
 		{
 			fn from(err: $error<$generic $(, $inst_generic)?>) -> &'static str {
 				err.as_str()
@@ -145,7 +145,7 @@ macro_rules! decl_error {
 
 		impl<$generic: $trait $(, $inst_generic: $instance)?> From<$error<$generic $(, $inst_generic)?>>
 			for $crate::sp_runtime::DispatchError
-		$( where $( $where_ty: $where_bound )* )?
+		$( where $( $where_ty: $where_bound ),* )?
 		{
 			fn from(err: $error<$generic $(, $inst_generic)?>) -> Self {
 				let index = <$generic::PalletInfo as $crate::traits::PalletInfo>
@@ -162,7 +162,7 @@ macro_rules! decl_error {
 
 		impl<$generic: $trait $(, $inst_generic: $instance)?> $crate::error::ModuleErrorMetadata
 			for $error<$generic $(, $inst_generic)?>
-		$( where $( $where_ty: $where_bound )* )?
+		$( where $( $where_ty: $where_bound ),* )?
 		{
 			fn metadata() -> &'static [$crate::error::ErrorMetadata] {
 				&[
diff --git a/substrate/frame/support/test/tests/instance.rs b/substrate/frame/support/test/tests/instance.rs
index 61df5d4eb8..6c90767f92 100644
--- a/substrate/frame/support/test/tests/instance.rs
+++ b/substrate/frame/support/test/tests/instance.rs
@@ -39,6 +39,7 @@ pub trait Currency {}
 // * Origin, Inherent, Event
 mod module1 {
 	use super::*;
+	use sp_std::ops::Add;
 
 	pub trait Trait<I>: system::Trait where <Self as system::Trait>::BlockNumber: From<u32> {
 		type Event: From<Event<Self, I>> + Into<<Self as system::Trait>::Event>;
@@ -82,7 +83,11 @@ mod module1 {
 	}
 
 	frame_support::decl_error! {
-		pub enum Error for Module<T: Trait<I>, I: Instance> where T::BlockNumber: From<u32> {
+		pub enum Error for Module<T: Trait<I>, I: Instance> where
+			T::BlockNumber: From<u32>,
+			T::BlockNumber: Add,
+			T::AccountId: AsRef<[u8]>,
+		{
 			/// Test
 			Test,
 		}