diff --git a/smartcontract/contracts/governance/src/lib.rs b/smartcontract/contracts/governance/src/lib.rs
index 00f8cb7..bc865fa 100644
--- a/smartcontract/contracts/governance/src/lib.rs
+++ b/smartcontract/contracts/governance/src/lib.rs
@@ -498,7 +498,12 @@ impl GovernanceContract {
             .get(&DataKey::QuorumPercent)
             .unwrap_or(50);
 
-        let quorum_threshold = (members.len() * quorum_percent) / 100;
+        let quorum_threshold = members
+            .len()
+            .checked_mul(quorum_percent)
+            .and_then(|votes| votes.checked_add(99))
+            .ok_or(Error::InvalidProposal)?
+            / 100;
         if proposal.total_votes < quorum_threshold {
             proposal.status = ProposalStatus::Expired;
         } else if proposal.votes_for > proposal.votes_against {
diff --git a/smartcontract/contracts/integration-tests/tests/cross_contract_invariants.rs b/smartcontract/contracts/integration-tests/tests/cross_contract_invariants.rs
index 2315f3f..911990f 100644
--- a/smartcontract/contracts/integration-tests/tests/cross_contract_invariants.rs
+++ b/smartcontract/contracts/integration-tests/tests/cross_contract_invariants.rs
@@ -91,6 +91,7 @@ fn governance_membership_lifecycle_updates_authorization() {
         &newbie,
     );
     gov.vote(&members[0], &add, &true);
+    gov.vote(&members[1], &add, &true);
     advance_seq(&env, 100);
     assert_eq!(gov.finalize(&members[0], &add), ProposalStatus::Passed);
     gov.execute_proposal(&admin, &add);
@@ -116,6 +117,7 @@ fn governance_membership_lifecycle_updates_authorization() {
         &members[1],
     );
     gov.vote(&members[0], &rem, &true);
+    gov.vote(&members[2], &rem, &true);
     advance_seq(&env, 100);
     assert_eq!(gov.finalize(&members[0], &rem), ProposalStatus::Passed);
     gov.execute_proposal(&admin, &rem);
@@ -175,6 +177,7 @@ fn terminal_operations_cannot_replay_across_contracts() {
         &gmembers[0],
     );
     gov.vote(&gmembers[0], &pid, &true);
+    gov.vote(&gmembers[1], &pid, &true);
     advance_seq(&env, 100);
     gov.finalize(&gmembers[0], &pid);
     gov.execute_proposal(&admin, &pid);
diff --git a/smartcontract/contracts/integration-tests/tests/governance_invariants.rs b/smartcontract/contracts/integration-tests/tests/governance_invariants.rs
index be4aff5..f45904a 100644
--- a/smartcontract/contracts/integration-tests/tests/governance_invariants.rs
+++ b/smartcontract/contracts/integration-tests/tests/governance_invariants.rs
@@ -96,6 +96,17 @@ fn quorum_not_met_expires() {
     );
 }
 
+/// INV-G4: quorum rounds up so a 50% quorum in a three-member DAO needs two votes.
+#[test]
+fn quorum_rounds_up_for_non_divisible_member_counts() {
+    let (env, _admin, members, c) = setup(3, 50, 100);
+    let id = mk_proposal(&c, &members[0]);
+    c.vote(&members[0], &id, &true);
+
+    advance_seq(&env, 200);
+    assert_eq!(c.finalize(&members[0], &id), ProposalStatus::Expired);
+}
+
 /// INV-G4: voting is closed once the proposal is finalized.
 #[test]
 fn cannot_vote_after_finalize() {