diff --git a/bin/node/executor/tests/submit_transaction.rs b/bin/node/executor/tests/submit_transaction.rs
index 784b140a13f1b..536cf486e38ae 100644
--- a/bin/node/executor/tests/submit_transaction.rs
+++ b/bin/node/executor/tests/submit_transaction.rs
@@ -181,9 +181,8 @@ fn submitted_transaction_should_be_valid() {
 			priority: 2_411_002_000_000,
 			requires: vec![],
 			provides: vec![(address, 0).encode()],
-			longevity: 127,
+			longevity: 128,
 			propagate: true,
 		});
 	});
 }
-
diff --git a/frame/collective/src/lib.rs b/frame/collective/src/lib.rs
index 5afdcd2b42189..d06d83b5bee6d 100644
--- a/frame/collective/src/lib.rs
+++ b/frame/collective/src/lib.rs
@@ -590,19 +590,20 @@ mod tests {
 	);
 
 	fn make_ext() -> sp_io::TestExternalities {
-		GenesisConfig {
+		let mut ext: sp_io::TestExternalities = GenesisConfig {
 			collective_Instance1: Some(collective::GenesisConfig {
 				members: vec![1, 2, 3],
 				phantom: Default::default(),
 			}),
 			collective: None,
-		}.build_storage().unwrap().into()
+		}.build_storage().unwrap().into();
+		ext.execute_with(|| System::set_block_number(1));
+		ext
 	}
 
 	#[test]
 	fn motions_basic_environment_works() {
 		make_ext().execute_with(|| {
-			System::set_block_number(1);
 			assert_eq!(Collective::members(), vec![1, 2, 3]);
 			assert_eq!(Collective::proposals(), Vec::<H256>::new());
 		});
@@ -615,7 +616,6 @@ mod tests {
 	#[test]
 	fn close_works() {
 		make_ext().execute_with(|| {
-			System::set_block_number(1);
 			let proposal = make_proposal(42);
 			let hash = BlakeTwo256::hash_of(&proposal);
 
@@ -644,7 +644,6 @@ mod tests {
 	#[test]
 	fn close_with_prime_works() {
 		make_ext().execute_with(|| {
-			System::set_block_number(1);
 			let proposal = make_proposal(42);
 			let hash = BlakeTwo256::hash_of(&proposal);
 			assert_ok!(Collective::set_members(Origin::ROOT, vec![1, 2, 3], Some(3)));
@@ -668,7 +667,6 @@ mod tests {
 	#[test]
 	fn close_with_voting_prime_works() {
 		make_ext().execute_with(|| {
-			System::set_block_number(1);
 			let proposal = make_proposal(42);
 			let hash = BlakeTwo256::hash_of(&proposal);
 			assert_ok!(Collective::set_members(Origin::ROOT, vec![1, 2, 3], Some(1)));
@@ -693,7 +691,6 @@ mod tests {
 	#[test]
 	fn removal_of_old_voters_votes_works() {
 		make_ext().execute_with(|| {
-			System::set_block_number(1);
 			let proposal = make_proposal(42);
 			let hash = BlakeTwo256::hash_of(&proposal);
 			let end = 4;
@@ -728,7 +725,6 @@ mod tests {
 	#[test]
 	fn removal_of_old_voters_votes_works_with_set_members() {
 		make_ext().execute_with(|| {
-			System::set_block_number(1);
 			let proposal = make_proposal(42);
 			let hash = BlakeTwo256::hash_of(&proposal);
 			let end = 4;
@@ -763,7 +759,6 @@ mod tests {
 	#[test]
 	fn propose_works() {
 		make_ext().execute_with(|| {
-			System::set_block_number(1);
 			let proposal = make_proposal(42);
 			let hash = proposal.blake2_256().into();
 			let end = 4;
@@ -793,7 +788,6 @@ mod tests {
 	#[test]
 	fn motions_ignoring_non_collective_proposals_works() {
 		make_ext().execute_with(|| {
-			System::set_block_number(1);
 			let proposal = make_proposal(42);
 			assert_noop!(
 				Collective::propose(Origin::signed(42), 3, Box::new(proposal.clone())),
@@ -805,7 +799,6 @@ mod tests {
 	#[test]
 	fn motions_ignoring_non_collective_votes_works() {
 		make_ext().execute_with(|| {
-			System::set_block_number(1);
 			let proposal = make_proposal(42);
 			let hash: H256 = proposal.blake2_256().into();
 			assert_ok!(Collective::propose(Origin::signed(1), 3, Box::new(proposal.clone())));
@@ -833,7 +826,6 @@ mod tests {
 	#[test]
 	fn motions_revoting_works() {
 		make_ext().execute_with(|| {
-			System::set_block_number(1);
 			let proposal = make_proposal(42);
 			let hash: H256 = proposal.blake2_256().into();
 			let end = 4;
@@ -885,7 +877,6 @@ mod tests {
 	#[test]
 	fn motions_reproposing_disapproved_works() {
 		make_ext().execute_with(|| {
-			System::set_block_number(1);
 			let proposal = make_proposal(42);
 			let hash: H256 = proposal.blake2_256().into();
 			assert_ok!(Collective::propose(Origin::signed(1), 3, Box::new(proposal.clone())));
@@ -899,7 +890,6 @@ mod tests {
 	#[test]
 	fn motions_disapproval_works() {
 		make_ext().execute_with(|| {
-			System::set_block_number(1);
 			let proposal = make_proposal(42);
 			let hash: H256 = proposal.blake2_256().into();
 			assert_ok!(Collective::propose(Origin::signed(1), 3, Box::new(proposal.clone())));
@@ -942,7 +932,6 @@ mod tests {
 	#[test]
 	fn motions_approval_works() {
 		make_ext().execute_with(|| {
-			System::set_block_number(1);
 			let proposal = make_proposal(42);
 			let hash: H256 = proposal.blake2_256().into();
 			assert_ok!(Collective::propose(Origin::signed(1), 2, Box::new(proposal.clone())));
diff --git a/frame/contracts/src/tests.rs b/frame/contracts/src/tests.rs
index 3c6cd62a441b2..04b9b1ee4ca77 100644
--- a/frame/contracts/src/tests.rs
+++ b/frame/contracts/src/tests.rs
@@ -279,7 +279,9 @@ impl ExtBuilder {
 			},
 			gas_price: self.gas_price,
 		}.assimilate_storage(&mut t).unwrap();
-		sp_io::TestExternalities::new(t)
+		let mut ext = sp_io::TestExternalities::new(t);
+		ext.execute_with(|| System::set_block_number(1));
+		ext
 	}
 }
 
diff --git a/frame/democracy/src/tests.rs b/frame/democracy/src/tests.rs
index f2544470aa722..1e2e6dc688277 100644
--- a/frame/democracy/src/tests.rs
+++ b/frame/democracy/src/tests.rs
@@ -160,7 +160,9 @@ fn new_test_ext() -> sp_io::TestExternalities {
 		balances: vec![(1, 10), (2, 20), (3, 30), (4, 40), (5, 50), (6, 60)],
 	}.assimilate_storage(&mut t).unwrap();
 	GenesisConfig::default().assimilate_storage(&mut t).unwrap();
-	sp_io::TestExternalities::new(t)
+	let mut ext = sp_io::TestExternalities::new(t);
+	ext.execute_with(|| System::set_block_number(1));
+	ext
 }
 
 type System = frame_system::Module<Test>;
diff --git a/frame/democracy/src/tests/cancellation.rs b/frame/democracy/src/tests/cancellation.rs
index c0e1b8b27ae40..424ec36dbeafc 100644
--- a/frame/democracy/src/tests/cancellation.rs
+++ b/frame/democracy/src/tests/cancellation.rs
@@ -21,7 +21,6 @@ use super::*;
 #[test]
 fn cancel_referendum_should_work() {
 	new_test_ext().execute_with(|| {
-		System::set_block_number(1);
 		let r = Democracy::inject_referendum(
 			2,
 			set_balance_proposal_hash_and_note(2),
diff --git a/frame/democracy/src/tests/lock_voting.rs b/frame/democracy/src/tests/lock_voting.rs
index c46bb47b893c3..e83d974a8dc27 100644
--- a/frame/democracy/src/tests/lock_voting.rs
+++ b/frame/democracy/src/tests/lock_voting.rs
@@ -140,7 +140,6 @@ fn no_locks_without_conviction_should_work() {
 #[test]
 fn lock_voting_should_work_with_delegation() {
 	new_test_ext().execute_with(|| {
-		System::set_block_number(1);
 		let r = Democracy::inject_referendum(
 			2,
 			set_balance_proposal_hash_and_note(2),
diff --git a/frame/democracy/src/tests/preimage.rs b/frame/democracy/src/tests/preimage.rs
index 1fb805f72630d..8d834c319e3c3 100644
--- a/frame/democracy/src/tests/preimage.rs
+++ b/frame/democracy/src/tests/preimage.rs
@@ -21,7 +21,6 @@ use super::*;
 #[test]
 fn missing_preimage_should_fail() {
 	new_test_ext().execute_with(|| {
-		System::set_block_number(1);
 		let r = Democracy::inject_referendum(
 			2,
 			set_balance_proposal_hash(2),
@@ -40,7 +39,6 @@ fn missing_preimage_should_fail() {
 #[test]
 fn preimage_deposit_should_be_required_and_returned() {
 	new_test_ext().execute_with(|| {
-		System::set_block_number(1);
 		// fee of 100 is too much.
 		PREIMAGE_BYTE_DEPOSIT.with(|v| *v.borrow_mut() = 100);
 		assert_noop!(
@@ -71,7 +69,6 @@ fn preimage_deposit_should_be_required_and_returned() {
 #[test]
 fn preimage_deposit_should_be_reapable_earlier_by_owner() {
 	new_test_ext().execute_with(|| {
-		System::set_block_number(1);
 		PREIMAGE_BYTE_DEPOSIT.with(|v| *v.borrow_mut() = 1);
 		assert_ok!(Democracy::note_preimage(Origin::signed(6), set_balance_proposal(2)));
 
@@ -93,7 +90,6 @@ fn preimage_deposit_should_be_reapable_earlier_by_owner() {
 #[test]
 fn preimage_deposit_should_be_reapable() {
 	new_test_ext().execute_with(|| {
-		System::set_block_number(1);
 		assert_noop!(
 				Democracy::reap_preimage(Origin::signed(5), set_balance_proposal_hash(2)),
 				Error::<Test>::PreimageMissing
@@ -122,7 +118,6 @@ fn preimage_deposit_should_be_reapable() {
 #[test]
 fn noting_imminent_preimage_for_free_should_work() {
 	new_test_ext().execute_with(|| {
-		System::set_block_number(1);
 		PREIMAGE_BYTE_DEPOSIT.with(|v| *v.borrow_mut() = 1);
 
 		let r = Democracy::inject_referendum(
@@ -152,7 +147,6 @@ fn noting_imminent_preimage_for_free_should_work() {
 #[test]
 fn reaping_imminent_preimage_should_fail() {
 	new_test_ext().execute_with(|| {
-		System::set_block_number(1);
 		let h = set_balance_proposal_hash_and_note(2);
 		let r = Democracy::inject_referendum(3, h, VoteThreshold::SuperMajorityApprove, 1);
 		assert_ok!(Democracy::vote(Origin::signed(1), r, aye(1)));
diff --git a/frame/democracy/src/tests/public_proposals.rs b/frame/democracy/src/tests/public_proposals.rs
index ef687146015aa..04246e86f1da4 100644
--- a/frame/democracy/src/tests/public_proposals.rs
+++ b/frame/democracy/src/tests/public_proposals.rs
@@ -21,7 +21,6 @@ use super::*;
 #[test]
 fn backing_for_should_work() {
 	new_test_ext().execute_with(|| {
-		System::set_block_number(1);
 		assert_ok!(propose_set_balance_and_note(1, 2, 2));
 		assert_ok!(propose_set_balance_and_note(1, 4, 4));
 		assert_ok!(propose_set_balance_and_note(1, 3, 3));
@@ -34,7 +33,6 @@ fn backing_for_should_work() {
 #[test]
 fn deposit_for_proposals_should_be_taken() {
 	new_test_ext().execute_with(|| {
-		System::set_block_number(1);
 		assert_ok!(propose_set_balance_and_note(1, 2, 5));
 		assert_ok!(Democracy::second(Origin::signed(2), 0));
 		assert_ok!(Democracy::second(Origin::signed(5), 0));
@@ -49,7 +47,6 @@ fn deposit_for_proposals_should_be_taken() {
 #[test]
 fn deposit_for_proposals_should_be_returned() {
 	new_test_ext().execute_with(|| {
-		System::set_block_number(1);
 		assert_ok!(propose_set_balance_and_note(1, 2, 5));
 		assert_ok!(Democracy::second(Origin::signed(2), 0));
 		assert_ok!(Democracy::second(Origin::signed(5), 0));
@@ -65,7 +62,6 @@ fn deposit_for_proposals_should_be_returned() {
 #[test]
 fn proposal_with_deposit_below_minimum_should_not_work() {
 	new_test_ext().execute_with(|| {
-		System::set_block_number(1);
 		assert_noop!(propose_set_balance(1, 2, 0), Error::<Test>::ValueLow);
 	});
 }
@@ -73,7 +69,6 @@ fn proposal_with_deposit_below_minimum_should_not_work() {
 #[test]
 fn poor_proposer_should_not_work() {
 	new_test_ext().execute_with(|| {
-		System::set_block_number(1);
 		assert_noop!(propose_set_balance(1, 2, 11), BalancesError::<Test, _>::InsufficientBalance);
 	});
 }
@@ -81,7 +76,6 @@ fn poor_proposer_should_not_work() {
 #[test]
 fn poor_seconder_should_not_work() {
 	new_test_ext().execute_with(|| {
-		System::set_block_number(1);
 		assert_ok!(propose_set_balance_and_note(2, 2, 11));
 		assert_noop!(Democracy::second(Origin::signed(1), 0), BalancesError::<Test, _>::InsufficientBalance);
 	});
diff --git a/frame/democracy/src/tests/scheduling.rs b/frame/democracy/src/tests/scheduling.rs
index 81120ea5b56c5..db9724deddc22 100644
--- a/frame/democracy/src/tests/scheduling.rs
+++ b/frame/democracy/src/tests/scheduling.rs
@@ -21,7 +21,6 @@ use super::*;
 #[test]
 fn simple_passing_should_work() {
 	new_test_ext().execute_with(|| {
-		System::set_block_number(1);
 		let r = Democracy::inject_referendum(
 			2,
 			set_balance_proposal_hash_and_note(2),
@@ -39,7 +38,6 @@ fn simple_passing_should_work() {
 #[test]
 fn simple_failing_should_work() {
 	new_test_ext().execute_with(|| {
-		System::set_block_number(1);
 		let r = Democracy::inject_referendum(
 			2,
 			set_balance_proposal_hash_and_note(2),
@@ -59,7 +57,6 @@ fn simple_failing_should_work() {
 #[test]
 fn ooo_inject_referendums_should_work() {
 	new_test_ext().execute_with(|| {
-		System::set_block_number(1);
 		let r1 = Democracy::inject_referendum(
 			3,
 			set_balance_proposal_hash_and_note(3),
@@ -90,7 +87,6 @@ fn ooo_inject_referendums_should_work() {
 #[test]
 fn delayed_enactment_should_work() {
 	new_test_ext().execute_with(|| {
-		System::set_block_number(1);
 		let r = Democracy::inject_referendum(
 			2,
 			set_balance_proposal_hash_and_note(2),
diff --git a/frame/democracy/src/tests/voting.rs b/frame/democracy/src/tests/voting.rs
index 06fde99cbdb5c..bdb8edb758ed5 100644
--- a/frame/democracy/src/tests/voting.rs
+++ b/frame/democracy/src/tests/voting.rs
@@ -99,7 +99,6 @@ fn single_proposal_should_work() {
 #[test]
 fn controversial_voting_should_work() {
 	new_test_ext().execute_with(|| {
-		System::set_block_number(1);
 		let r = Democracy::inject_referendum(
 			2,
 			set_balance_proposal_hash_and_note(2),
@@ -126,7 +125,6 @@ fn controversial_voting_should_work() {
 #[test]
 fn controversial_low_turnout_voting_should_work() {
 	new_test_ext().execute_with(|| {
-		System::set_block_number(1);
 		let r = Democracy::inject_referendum(
 			2,
 			set_balance_proposal_hash_and_note(2),
@@ -151,7 +149,6 @@ fn passing_low_turnout_voting_should_work() {
 		assert_eq!(Balances::free_balance(42), 0);
 		assert_eq!(Balances::total_issuance(), 210);
 
-		System::set_block_number(1);
 		let r = Democracy::inject_referendum(
 			2,
 			set_balance_proposal_hash_and_note(2),
diff --git a/frame/elections-phragmen/src/lib.rs b/frame/elections-phragmen/src/lib.rs
index 9a9e3c3143856..12307fe7128dc 100644
--- a/frame/elections-phragmen/src/lib.rs
+++ b/frame/elections-phragmen/src/lib.rs
@@ -1040,7 +1040,7 @@ mod tests {
 			VOTING_BOND.with(|v| *v.borrow_mut() = self.voter_bond);
 			TERM_DURATION.with(|v| *v.borrow_mut() = self.term_duration);
 			DESIRED_RUNNERS_UP.with(|v| *v.borrow_mut() = self.desired_runners_up);
-			GenesisConfig {
+			let mut ext: sp_io::TestExternalities = GenesisConfig {
 				pallet_balances: Some(pallet_balances::GenesisConfig::<Test>{
 					balances: vec![
 						(1, 10 * self.balance_factor),
@@ -1051,7 +1051,9 @@ mod tests {
 						(6, 60 * self.balance_factor)
 					],
 				}),
-			}.build_storage().unwrap().into()
+			}.build_storage().unwrap().into();
+			ext.execute_with(|| System::set_block_number(1));
+			ext
 		}
 	}
 
@@ -1072,7 +1074,6 @@ mod tests {
 	#[test]
 	fn params_should_work() {
 		ExtBuilder::default().build().execute_with(|| {
-			System::set_block_number(1);
 			assert_eq!(Elections::desired_members(), 2);
 			assert_eq!(Elections::term_duration(), 5);
 			assert_eq!(Elections::election_rounds(), 0);
@@ -1096,7 +1097,6 @@ mod tests {
 			.build()
 			.execute_with(||
 		{
-			System::set_block_number(1);
 			assert_eq!(Elections::term_duration(), 0);
 			assert_eq!(Elections::desired_members(), 2);
 			assert_eq!(Elections::election_rounds(), 0);
@@ -1537,10 +1537,9 @@ mod tests {
 			assert_eq!(balances(&5), (45, 5));
 
 			assert_ok!(Elections::report_defunct_voter(Origin::signed(5), 3));
-			assert_eq!(
-				System::events()[7].event,
-				Event::elections(RawEvent::VoterReported(3, 5, true))
-			);
+			assert!(System::events().iter().any(|event| {
+				event.event == Event::elections(RawEvent::VoterReported(3, 5, true))
+			}));
 
 			assert_eq!(balances(&3), (28, 0));
 			assert_eq!(balances(&5), (47, 5));
@@ -1566,10 +1565,9 @@ mod tests {
 			assert_eq!(balances(&5), (45, 5));
 
 			assert_ok!(Elections::report_defunct_voter(Origin::signed(5), 4));
-			assert_eq!(
-				System::events()[7].event,
-				Event::elections(RawEvent::VoterReported(4, 5, false))
-			);
+			assert!(System::events().iter().any(|event| {
+				event.event == Event::elections(RawEvent::VoterReported(4, 5, false))
+			}));
 
 			assert_eq!(balances(&4), (35, 5));
 			assert_eq!(balances(&5), (45, 3));
@@ -1977,10 +1975,9 @@ mod tests {
 			// 5 is an outgoing loser. will also get slashed.
 			assert_eq!(balances(&5), (45, 2));
 
-			assert_eq!(
-				System::events()[6].event,
-				Event::elections(RawEvent::NewTerm(vec![(4, 40), (5, 50)])),
-			);
+			assert!(System::events().iter().any(|event| {
+				event.event == Event::elections(RawEvent::NewTerm(vec![(4, 40), (5, 50)]))
+			}));
 		})
 	}
 
diff --git a/frame/elections/src/mock.rs b/frame/elections/src/mock.rs
index b82e73d512aa6..2898be26ca300 100644
--- a/frame/elections/src/mock.rs
+++ b/frame/elections/src/mock.rs
@@ -208,7 +208,7 @@ impl ExtBuilder {
 		VOTING_FEE.with(|v| *v.borrow_mut() = self.voting_fee);
 		PRESENT_SLASH_PER_VOTER.with(|v| *v.borrow_mut() = self.bad_presentation_punishment);
 		DECAY_RATIO.with(|v| *v.borrow_mut() = self.decay_ratio);
-		GenesisConfig {
+		let mut ext: sp_io::TestExternalities = GenesisConfig {
 			pallet_balances: Some(pallet_balances::GenesisConfig::<Test>{
 				balances: vec![
 					(1, 10 * self.balance_factor),
@@ -225,7 +225,9 @@ impl ExtBuilder {
 				presentation_duration: 2,
 				term_duration: 5,
 			}),
-		}.build_storage().unwrap().into()
+		}.build_storage().unwrap().into();
+		ext.execute_with(|| System::set_block_number(1));
+		ext
 	}
 }
 
diff --git a/frame/elections/src/tests.rs b/frame/elections/src/tests.rs
index e26f0312903fc..64b01f12e0cfe 100644
--- a/frame/elections/src/tests.rs
+++ b/frame/elections/src/tests.rs
@@ -26,7 +26,6 @@ use frame_support::{assert_ok, assert_err, assert_noop};
 #[test]
 fn params_should_work() {
 	ExtBuilder::default().build().execute_with(|| {
-		System::set_block_number(1);
 		assert_eq!(Elections::next_vote_from(1), 4);
 		assert_eq!(Elections::next_vote_from(4), 4);
 		assert_eq!(Elections::next_vote_from(5), 8);
@@ -408,8 +407,6 @@ fn voting_locking_stake_and_reserving_bond_works() {
 #[test]
 fn voting_without_any_candidate_count_should_not_work() {
 	ExtBuilder::default().build().execute_with(|| {
-		System::set_block_number(1);
-
 		assert_eq!(Elections::candidates().len(), 0);
 
 		assert_noop!(
@@ -422,8 +419,6 @@ fn voting_without_any_candidate_count_should_not_work() {
 #[test]
 fn voting_setting_an_approval_vote_count_more_than_candidate_count_should_not_work() {
 	ExtBuilder::default().build().execute_with(|| {
-		System::set_block_number(1);
-
 		assert_ok!(Elections::submit_candidacy(Origin::signed(5), 0));
 		assert_eq!(Elections::candidates().len(), 1);
 
@@ -437,8 +432,6 @@ fn voting_setting_an_approval_vote_count_more_than_candidate_count_should_not_wo
 #[test]
 fn voting_resubmitting_approvals_should_work() {
 	ExtBuilder::default().build().execute_with(|| {
-		System::set_block_number(1);
-
 		assert_ok!(Elections::submit_candidacy(Origin::signed(5), 0));
 		assert_ok!(Elections::set_approvals(Origin::signed(4), vec![true], 0, 0, 40));
 
@@ -456,8 +449,6 @@ fn voting_resubmitting_approvals_should_work() {
 #[test]
 fn voting_retracting_voter_should_work() {
 	ExtBuilder::default().build().execute_with(|| {
-		System::set_block_number(1);
-
 		assert_ok!(Elections::submit_candidacy(Origin::signed(5), 0));
 		assert_eq!(Elections::candidates().len(), 1);
 
@@ -501,7 +492,6 @@ fn voting_retracting_voter_should_work() {
 #[test]
 fn voting_invalid_retraction_index_should_not_work() {
 	ExtBuilder::default().build().execute_with(|| {
-		System::set_block_number(1);
 		assert_ok!(Elections::submit_candidacy(Origin::signed(3), 0));
 
 		assert_ok!(Elections::set_approvals(Origin::signed(1), vec![true], 0, 0, 10));
@@ -514,7 +504,6 @@ fn voting_invalid_retraction_index_should_not_work() {
 #[test]
 fn voting_overflow_retraction_index_should_not_work() {
 	ExtBuilder::default().build().execute_with(|| {
-		System::set_block_number(1);
 		assert_ok!(Elections::submit_candidacy(Origin::signed(3), 0));
 
 		assert_ok!(Elections::set_approvals(Origin::signed(1), vec![true], 0, 0, 10));
@@ -525,7 +514,6 @@ fn voting_overflow_retraction_index_should_not_work() {
 #[test]
 fn voting_non_voter_retraction_should_not_work() {
 	ExtBuilder::default().build().execute_with(|| {
-		System::set_block_number(1);
 		assert_ok!(Elections::submit_candidacy(Origin::signed(3), 0));
 
 		assert_ok!(Elections::set_approvals(Origin::signed(1), vec![true], 0, 0, 10));
@@ -740,7 +728,6 @@ fn retracting_inactive_voter_by_nonvoter_should_not_work() {
 #[test]
 fn candidacy_simple_candidate_submission_should_work() {
 	ExtBuilder::default().build().execute_with(|| {
-		System::set_block_number(1);
 		assert_eq!(Elections::candidates(), Vec::<u64>::new());
 		assert_eq!(Elections::candidate_reg_info(1), None);
 		assert_eq!(Elections::candidate_reg_info(2), None);
@@ -768,7 +755,6 @@ fn candidacy_submission_using_free_slot_should_work() {
 	let mut t = new_test_ext_with_candidate_holes();
 
 	t.execute_with(|| {
-		System::set_block_number(1);
 		assert_eq!(Elections::candidates(), vec![0, 0, 1]);
 
 		assert_ok!(Elections::submit_candidacy(Origin::signed(2), 1));
@@ -784,7 +770,6 @@ fn candidacy_submission_using_alternative_free_slot_should_work() {
 	let mut t = new_test_ext_with_candidate_holes();
 
 	t.execute_with(|| {
-		System::set_block_number(1);
 		assert_eq!(Elections::candidates(), vec![0, 0, 1]);
 
 		assert_ok!(Elections::submit_candidacy(Origin::signed(2), 0));
@@ -800,7 +785,6 @@ fn candidacy_submission_not_using_free_slot_should_not_work() {
 	let mut t = new_test_ext_with_candidate_holes();
 
 	t.execute_with(|| {
-		System::set_block_number(1);
 		assert_noop!(
 			Elections::submit_candidacy(Origin::signed(4), 3),
 			Error::<Test>::InvalidCandidateSlot
@@ -811,7 +795,6 @@ fn candidacy_submission_not_using_free_slot_should_not_work() {
 #[test]
 fn candidacy_bad_candidate_slot_submission_should_not_work() {
 	ExtBuilder::default().build().execute_with(|| {
-		System::set_block_number(1);
 		assert_eq!(Elections::candidates(), Vec::<u64>::new());
 		assert_noop!(
 			Elections::submit_candidacy(Origin::signed(1), 1),
@@ -823,7 +806,6 @@ fn candidacy_bad_candidate_slot_submission_should_not_work() {
 #[test]
 fn candidacy_non_free_candidate_slot_submission_should_not_work() {
 	ExtBuilder::default().build().execute_with(|| {
-		System::set_block_number(1);
 		assert_eq!(Elections::candidates(), Vec::<u64>::new());
 		assert_ok!(Elections::submit_candidacy(Origin::signed(1), 0));
 		assert_eq!(Elections::candidates(), vec![1]);
@@ -837,7 +819,6 @@ fn candidacy_non_free_candidate_slot_submission_should_not_work() {
 #[test]
 fn candidacy_dupe_candidate_submission_should_not_work() {
 	ExtBuilder::default().build().execute_with(|| {
-		System::set_block_number(1);
 		assert_eq!(Elections::candidates(), Vec::<u64>::new());
 		assert_ok!(Elections::submit_candidacy(Origin::signed(1), 0));
 		assert_eq!(Elections::candidates(), vec![1]);
@@ -851,7 +832,6 @@ fn candidacy_dupe_candidate_submission_should_not_work() {
 #[test]
 fn candidacy_poor_candidate_submission_should_not_work() {
 	ExtBuilder::default().build().execute_with(|| {
-		System::set_block_number(1);
 		assert_eq!(Elections::candidates(), Vec::<u64>::new());
 		assert_noop!(
 			Elections::submit_candidacy(Origin::signed(7), 0),
@@ -863,8 +843,6 @@ fn candidacy_poor_candidate_submission_should_not_work() {
 #[test]
 fn election_voting_should_work() {
 	ExtBuilder::default().build().execute_with(|| {
-		System::set_block_number(1);
-
 		assert_ok!(Elections::submit_candidacy(Origin::signed(5), 0));
 
 		assert_ok!(Elections::set_approvals(Origin::signed(1), vec![true], 0, 0, 10));
@@ -892,8 +870,6 @@ fn election_voting_should_work() {
 #[test]
 fn election_proxy_voting_should_work() {
 	ExtBuilder::default().build().execute_with(|| {
-		System::set_block_number(1);
-
 		assert_ok!(Elections::submit_candidacy(Origin::signed(5), 0));
 
 		<Proxy<Test>>::insert(11, 1);
diff --git a/frame/generic-asset/src/mock.rs b/frame/generic-asset/src/mock.rs
index 8db140d90c666..c805b793bc7b4 100644
--- a/frame/generic-asset/src/mock.rs
+++ b/frame/generic-asset/src/mock.rs
@@ -127,16 +127,17 @@ impl ExtBuilder {
 		let mut t = frame_system::GenesisConfig::default().build_storage::<Test>().unwrap();
 
 		GenesisConfig::<Test> {
-				assets: vec![self.asset_id],
-				endowed_accounts: self.accounts,
-				initial_balance: self.initial_balance,
-				next_asset_id: self.next_asset_id,
-				staking_asset_id: 16000,
-				spending_asset_id: 16001,
-			}
-			.assimilate_storage(&mut t).unwrap();
-
-		t.into()
+			assets: vec![self.asset_id],
+			endowed_accounts: self.accounts,
+			initial_balance: self.initial_balance,
+			next_asset_id: self.next_asset_id,
+			staking_asset_id: 16000,
+			spending_asset_id: 16001,
+		}.assimilate_storage(&mut t).unwrap();
+
+		let mut ext = sp_io::TestExternalities::new(t);
+		ext.execute_with(|| System::set_block_number(1));
+		ext
 	}
 }
 
diff --git a/frame/im-online/src/mock.rs b/frame/im-online/src/mock.rs
index 1fd1bcbdfe386..3dc0543d8881b 100644
--- a/frame/im-online/src/mock.rs
+++ b/frame/im-online/src/mock.rs
@@ -175,7 +175,7 @@ pub type System = frame_system::Module<Runtime>;
 pub type Session = pallet_session::Module<Runtime>;
 
 pub fn advance_session() {
-	let now = System::block_number();
+	let now = System::block_number().max(1);
 	System::set_block_number(now + 1);
 	Session::rotate_session();
 	assert_eq!(Session::current_index(), (now / Period::get()) as u32);
diff --git a/frame/offences/src/mock.rs b/frame/offences/src/mock.rs
index 7ddbc6726d05f..e464200396ebd 100644
--- a/frame/offences/src/mock.rs
+++ b/frame/offences/src/mock.rs
@@ -128,7 +128,9 @@ impl_outer_event! {
 
 pub fn new_test_ext() -> sp_io::TestExternalities {
 	let t = frame_system::GenesisConfig::default().build_storage::<Runtime>().unwrap();
-	t.into()
+	let mut ext = sp_io::TestExternalities::new(t);
+	ext.execute_with(|| System::set_block_number(1));
+	ext
 }
 
 /// Offences module.
diff --git a/frame/recovery/src/tests.rs b/frame/recovery/src/tests.rs
index 9c644291c906d..fb993043a5b00 100644
--- a/frame/recovery/src/tests.rs
+++ b/frame/recovery/src/tests.rs
@@ -240,7 +240,7 @@ fn initiate_recovery_works() {
 		assert_eq!(Balances::reserved_balance(1), 10);
 		// Recovery status object is created correctly
 		let recovery_status = ActiveRecovery {
-			created: 1,
+			created: 0,
 			deposit: 10,
 			friends: vec![],
 		};
@@ -288,7 +288,7 @@ fn vouch_recovery_works() {
 		assert_ok!(Recovery::vouch_recovery(Origin::signed(3), 5, 1));
 		// Final recovery status object is updated correctly
 		let recovery_status = ActiveRecovery {
-			created: 1,
+			created: 0,
 			deposit: 10,
 			friends: vec![2, 3, 4],
 		};
diff --git a/frame/staking/src/mock.rs b/frame/staking/src/mock.rs
index d8d9a55032b4f..b90064ae47f4d 100644
--- a/frame/staking/src/mock.rs
+++ b/frame/staking/src/mock.rs
@@ -489,6 +489,7 @@ impl ExtBuilder {
 		// This must be ensured by having `timestamp::on_initialize` called before
 		// `staking::on_initialize`
 		ext.execute_with(|| {
+			System::set_block_number(1);
 			Timestamp::set_timestamp(INIT_TIMESTAMP);
 		});
 
diff --git a/frame/staking/src/tests.rs b/frame/staking/src/tests.rs
index abd3c00ae8c01..01334b918f5f9 100644
--- a/frame/staking/src/tests.rs
+++ b/frame/staking/src/tests.rs
@@ -1706,7 +1706,6 @@ fn new_era_elects_correct_number_of_validators() {
 			assert_eq!(Staking::validator_count(), 1);
 			assert_eq!(validator_controllers().len(), 1);
 
-			System::set_block_number(1);
 			Session::on_initialize(System::block_number());
 
 			assert_eq!(validator_controllers().len(), 1);
diff --git a/frame/system/src/lib.rs b/frame/system/src/lib.rs
index 92948544ce11e..2d965b44f0777 100644
--- a/frame/system/src/lib.rs
+++ b/frame/system/src/lib.rs
@@ -366,7 +366,7 @@ decl_storage! {
 		ExtrinsicData get(fn extrinsic_data): map hasher(twox_64_concat) u32 => Vec<u8>;
 
 		/// The current block number being processed. Set by `execute_block`.
-		Number get(fn block_number) build(|_| 1.into()): T::BlockNumber;
+		Number get(fn block_number): T::BlockNumber;
 
 		/// Hash of the previous block.
 		ParentHash get(fn parent_hash) build(|_| hash69()): T::Hash;
@@ -749,6 +749,10 @@ impl<T: Trait> Module<T> {
 	/// This will update storage entries that correspond to the specified topics.
 	/// It is expected that light-clients could subscribe to this topics.
 	pub fn deposit_event_indexed(topics: &[T::Hash], event: T::Event) {
+		let block_number = Self::block_number();
+		// Don't populate events on genesis.
+		if block_number.is_zero() { return }
+
 		let phase = ExecutionPhase::get().unwrap_or_default();
 		let event = EventRecord {
 			phase,
@@ -781,10 +785,9 @@ impl<T: Trait> Module<T> {
 			return;
 		}
 
-		let block_no = Self::block_number();
 		for topic in topics {
 			// The same applies here.
-			if <EventTopics<T>>::append(topic, &[(block_no, event_idx)]).is_err() {
+			if <EventTopics<T>>::append(topic, &[(block_number, event_idx)]).is_err() {
 				return;
 			}
 		}
@@ -2041,6 +2044,7 @@ mod tests {
 		let mut ext = new_test_ext();
 		ext.register_extension(sp_core::traits::CallInWasmExt::new(executor));
 		ext.execute_with(|| {
+			System::set_block_number(1);
 			System::set_code(
 				RawOrigin::Root.into(),
 				substrate_test_runtime_client::runtime::WASM_BINARY.to_vec(),
@@ -2068,4 +2072,18 @@ mod tests {
 			).unwrap();
 		});
 	}
+
+	#[test]
+	fn events_not_emitted_during_genesis() {
+		new_test_ext().execute_with(|| {
+			// Block Number is zero at genesis
+			assert!(System::block_number().is_zero());
+			System::on_created_account(Default::default());
+			assert!(System::events().is_empty());
+			// Events will be emitted starting on block 1
+			System::set_block_number(1);
+			System::on_created_account(Default::default());
+			assert!(System::events().len() == 1);
+		});
+	}
 }
diff --git a/frame/utility/src/lib.rs b/frame/utility/src/lib.rs
index 0b60532c3dd23..2f7b11bdaac7c 100644
--- a/frame/utility/src/lib.rs
+++ b/frame/utility/src/lib.rs
@@ -661,7 +661,9 @@ mod tests {
 		pallet_balances::GenesisConfig::<Test> {
 			balances: vec![(1, 10), (2, 10), (3, 10), (4, 10), (5, 10)],
 		}.assimilate_storage(&mut t).unwrap();
-		t.into()
+		let mut ext = sp_io::TestExternalities::new(t);
+		ext.execute_with(|| System::set_block_number(1));
+		ext
 	}
 
 	fn last_event() -> TestEvent {
diff --git a/frame/vesting/src/lib.rs b/frame/vesting/src/lib.rs
index 3f7cdf3170963..b7ff091d326f3 100644
--- a/frame/vesting/src/lib.rs
+++ b/frame/vesting/src/lib.rs
@@ -452,7 +452,9 @@ mod tests {
 					(12, 10, 20, 5 * self.existential_deposit)
 				],
 			}.assimilate_storage(&mut t).unwrap();
-			t.into()
+			let mut ext = sp_io::TestExternalities::new(t);
+			ext.execute_with(|| System::set_block_number(1));
+			ext
 		}
 	}
 
@@ -462,7 +464,6 @@ mod tests {
 			.existential_deposit(256)
 			.build()
 			.execute_with(|| {
-				assert_eq!(System::block_number(), 1);
 				let user1_free_balance = Balances::free_balance(&1);
 				let user2_free_balance = Balances::free_balance(&2);
 				let user12_free_balance = Balances::free_balance(&12);
@@ -521,7 +522,6 @@ mod tests {
 			.existential_deposit(10)
 			.build()
 			.execute_with(|| {
-				assert_eq!(System::block_number(), 1);
 				let user1_free_balance = Balances::free_balance(&1);
 				assert_eq!(user1_free_balance, 100); // Account 1 has free balance
 				// Account 1 has only 5 units vested at block 1 (plus 50 unvested)
@@ -539,7 +539,6 @@ mod tests {
 			.existential_deposit(10)
 			.build()
 			.execute_with(|| {
-				assert_eq!(System::block_number(), 1);
 				let user1_free_balance = Balances::free_balance(&1);
 				assert_eq!(user1_free_balance, 100); // Account 1 has free balance
 				// Account 1 has only 5 units vested at block 1 (plus 50 unvested)
@@ -555,7 +554,6 @@ mod tests {
 			.existential_deposit(10)
 			.build()
 			.execute_with(|| {
-				assert_eq!(System::block_number(), 1);
 				let user1_free_balance = Balances::free_balance(&1);
 				assert_eq!(user1_free_balance, 100); // Account 1 has free balance
 				// Account 1 has only 5 units vested at block 1 (plus 50 unvested)
@@ -571,7 +569,6 @@ mod tests {
 			.existential_deposit(10)
 			.build()
 			.execute_with(|| {
-				assert_eq!(System::block_number(), 1);
 				assert_ok!(Balances::transfer(Some(3).into(), 1, 100));
 				assert_ok!(Balances::transfer(Some(3).into(), 2, 100));
 
@@ -599,7 +596,6 @@ mod tests {
 			.existential_deposit(256)
 			.build()
 			.execute_with(|| {
-				assert_eq!(System::block_number(), 1);
 				let user12_free_balance = Balances::free_balance(&12);
 
 				assert_eq!(user12_free_balance, 2560); // Account 12 has free balance
@@ -625,7 +621,6 @@ mod tests {
 			.existential_deposit(256)
 			.build()
 			.execute_with(|| {
-				assert_eq!(System::block_number(), 1);
 				let user3_free_balance = Balances::free_balance(&3);
 				let user4_free_balance = Balances::free_balance(&4);
 				assert_eq!(user3_free_balance, 256 * 30);
@@ -669,7 +664,6 @@ mod tests {
 			.existential_deposit(256)
 			.build()
 			.execute_with(|| {
-				assert_eq!(System::block_number(), 1);
 				let user2_free_balance = Balances::free_balance(&2);
 				let user4_free_balance = Balances::free_balance(&4);
 				assert_eq!(user2_free_balance, 256 * 20);