diff --git a/pallets/minter-reward/src/lib.rs b/pallets/minter-reward/src/lib.rs
index a1e204c360..1f1930afea 100644
--- a/pallets/minter-reward/src/lib.rs
+++ b/pallets/minter-reward/src/lib.rs
@@ -196,13 +196,13 @@ pub mod pallet {
 				MaximumVtokenMinted::<T>::get();
 
 			let last_block_diff = n.saturating_sub(last_max_minted_block);
+			let start_block_diff = n.saturating_sub(started_block_num);
 
 			if (last_block_diff >= T::RewardWindow::get() && started_block_num > Zero::zero()) ||
 				(last_block_diff < T::RewardWindow::get() &&
-					last_block_diff >= max_extended_period &&
+					start_block_diff >= max_extended_period &&
 					started_block_num > Zero::zero())
 			{
-				let start_block_diff = n.saturating_sub(started_block_num);
 				let period = BalanceOf::<T>::from(start_block_diff.saturated_into::<u32>());
 
 				let total_reward = period.saturating_mul(RewardPerBlock::<T>::get());
diff --git a/pallets/minter-reward/src/tests.rs b/pallets/minter-reward/src/tests.rs
index 0e93950988..74e9ca513b 100644
--- a/pallets/minter-reward/src/tests.rs
+++ b/pallets/minter-reward/src/tests.rs
@@ -150,8 +150,21 @@ fn minter_reward_should_work() {
 			(12, 56, CurrencyId::VToken(TokenSymbol::DOT))
 		);
 
-		run_to_block(41);
+		// start block is 2, max extended block is 20, block 22 should still be the last block of
+		// maximum_vtoken(12, 56, CurrencyId::VToken(TokenSymbol::DOT))
+		run_to_block(22);
+		assert_eq!(
+			MinterReward::maximum_vtoken_minted(),
+			(12, 56, CurrencyId::VToken(TokenSymbol::DOT))
+		);
+
+		// 23-2=21 >20, so the previous round will be ended and new round will be started.
+		run_to_block(23);
 		assert_eq!(MinterReward::current_round_start_at(), 0);
+		assert_eq!(
+			MinterReward::maximum_vtoken_minted(),
+			(0, 0, CurrencyId::Native(TokenSymbol::BNC))
+		);
 
 		run_to_block(42);
 		assert_ok!(VtokenMint::mint(Origin::signed(ALICE), vDOT, to_sell_vdot + 20));
@@ -160,5 +173,8 @@ fn minter_reward_should_work() {
 		// 60 blocks to be a halving reward cycle
 		run_to_block(61);
 		assert_eq!(MinterReward::reward_per_block(), 150);
+
+		// 42+20=62. When block number reaches 63, the previous round will be ended, since no new
+		// minting action is taken
 	});
 }