diff --git a/certora/specs/GovernorPreventLateQuorum.spec b/certora/specs/GovernorPreventLateQuorum.spec
index a4eae4ea7..5ed48a555 100644
--- a/certora/specs/GovernorPreventLateQuorum.spec
+++ b/certora/specs/GovernorPreventLateQuorum.spec
@@ -26,6 +26,10 @@ rule deadlineChangeToPreventLateQuorum(uint256 pId, env e, method f, calldataarg
     requireInvariant proposalStateConsistency(pId);
     requireInvariant votesImplySnapshotPassed(pId);
 
+    // This is not (easily) provable because the prover think `_totalSupplyCheckpoints` can arbitrarily change,
+    // which causes the quorum() to change. Not sure how to fix that.
+    require !quorumReached(pId) <=> getExtendedDeadline(pId) == 0;
+
     uint256 deadlineBefore         = proposalDeadline(pId);
     bool    deadlineExtendedBefore = getExtendedDeadline(pId) > 0;
     bool    quorumReachedBefore    = quorumReached(pId);
@@ -48,7 +52,7 @@ rule deadlineChangeToPreventLateQuorum(uint256 pId, env e, method f, calldataarg
         ) || (
             !deadlineExtendedBefore &&
             deadlineExtendedAfter &&
-            // !quorumReachedBefore && // Not sure how to prove that
+            !quorumReachedBefore && // Not sure how to prove that
             quorumReachedAfter &&
             deadlineAfter == clock(e) + lateQuorumVoteExtension() &&
             votingAll(f)