diff --git a/protocol/synchronizer/synchronizer_test.go b/protocol/synchronizer/synchronizer_test.go
index a8b6516d..750d9e28 100644
--- a/protocol/synchronizer/synchronizer_test.go
+++ b/protocol/synchronizer/synchronizer_test.go
@@ -180,6 +180,7 @@ func TestAdvanceView(t *testing.T) {
 		{name: "signers=4/Simple___/__/TC/AC", tr: S, qc: F, tc: T, ac: T, firstSignerIdx: 0, wantView: 2},
 		{name: "signers=4/Simple___/QC/__/__", tr: S, qc: T, tc: F, ac: F, firstSignerIdx: 0, wantView: 2},
 		{name: "signers=4/Simple___/QC/__/AC", tr: S, qc: T, tc: F, ac: T, firstSignerIdx: 0, wantView: 2},
+		{name: "signers=4/Simple___/QC/TC/__", tr: S, qc: T, tc: T, ac: F, firstSignerIdx: 0, wantView: 2},
 		{name: "signers=4/Simple___/QC/TC/AC", tr: S, qc: T, tc: T, ac: T, firstSignerIdx: 0, wantView: 2},
 		{name: "signers=4/Aggregate/__/__/__", tr: A, qc: F, tc: F, ac: F, firstSignerIdx: 0, wantView: 1}, // empty syncInfo, should not advance view
 		{name: "signers=4/Aggregate/__/__/AC", tr: A, qc: F, tc: F, ac: T, firstSignerIdx: 0, wantView: 2},
@@ -187,14 +188,16 @@ func TestAdvanceView(t *testing.T) {
 		{name: "signers=4/Aggregate/__/TC/AC", tr: A, qc: F, tc: T, ac: T, firstSignerIdx: 0, wantView: 2},
 		{name: "signers=4/Aggregate/QC/__/__", tr: A, qc: T, tc: F, ac: F, firstSignerIdx: 0, wantView: 1}, // aggregate timeout rule ignores quorum cert, will not advance view
 		{name: "signers=4/Aggregate/QC/__/AC", tr: A, qc: T, tc: F, ac: T, firstSignerIdx: 0, wantView: 2},
+		{name: "signers=4/Aggregate/QC/TC/__", tr: A, qc: T, tc: T, ac: F, firstSignerIdx: 0, wantView: 2},
 		{name: "signers=4/Aggregate/QC/TC/AC", tr: A, qc: T, tc: T, ac: T, firstSignerIdx: 0, wantView: 2},
-		// three signers; quorum reacted, advance view
+		// three signers; quorum reached, advance view
 		{name: "signers=3/Simple___/__/__/__", tr: S, qc: F, tc: F, ac: F, firstSignerIdx: 1, wantView: 1}, // empty syncInfo, should not advance view
 		{name: "signers=3/Simple___/__/__/AC", tr: S, qc: F, tc: F, ac: T, firstSignerIdx: 1, wantView: 1}, // simple timeout rule ignores aggregate timeout cert, will not advance view
 		{name: "signers=3/Simple___/__/TC/__", tr: S, qc: F, tc: T, ac: F, firstSignerIdx: 1, wantView: 2},
 		{name: "signers=3/Simple___/__/TC/AC", tr: S, qc: F, tc: T, ac: T, firstSignerIdx: 1, wantView: 2},
 		{name: "signers=3/Simple___/QC/__/__", tr: S, qc: T, tc: F, ac: F, firstSignerIdx: 1, wantView: 2},
 		{name: "signers=3/Simple___/QC/__/AC", tr: S, qc: T, tc: F, ac: T, firstSignerIdx: 1, wantView: 2},
+		{name: "signers=3/Simple___/QC/TC/__", tr: S, qc: T, tc: T, ac: F, firstSignerIdx: 1, wantView: 2},
 		{name: "signers=3/Simple___/QC/TC/AC", tr: S, qc: T, tc: T, ac: T, firstSignerIdx: 1, wantView: 2},
 		{name: "signers=3/Aggregate/__/__/__", tr: A, qc: F, tc: F, ac: F, firstSignerIdx: 1, wantView: 1}, // empty syncInfo, should not advance view
 		{name: "signers=3/Aggregate/__/__/AC", tr: A, qc: F, tc: F, ac: T, firstSignerIdx: 1, wantView: 2},
@@ -202,6 +205,7 @@ func TestAdvanceView(t *testing.T) {
 		{name: "signers=3/Aggregate/__/TC/AC", tr: A, qc: F, tc: T, ac: T, firstSignerIdx: 1, wantView: 2},
 		{name: "signers=3/Aggregate/QC/__/__", tr: A, qc: T, tc: F, ac: F, firstSignerIdx: 1, wantView: 1}, // aggregate timeout rule ignores quorum cert, will not advance view
 		{name: "signers=3/Aggregate/QC/__/AC", tr: A, qc: T, tc: F, ac: T, firstSignerIdx: 1, wantView: 2},
+		{name: "signers=3/Aggregate/QC/TC/__", tr: A, qc: T, tc: T, ac: F, firstSignerIdx: 1, wantView: 2},
 		{name: "signers=3/Aggregate/QC/TC/AC", tr: A, qc: T, tc: T, ac: T, firstSignerIdx: 1, wantView: 2},
 		// only two signers; no quorum reached, should not advance view
 		{name: "signers=2/Simple___/__/__/__", tr: S, qc: F, tc: F, ac: F, firstSignerIdx: 2, wantView: 1}, // empty syncInfo, should not advance view
@@ -210,6 +214,7 @@ func TestAdvanceView(t *testing.T) {
 		{name: "signers=2/Simple___/__/TC/AC", tr: S, qc: F, tc: T, ac: T, firstSignerIdx: 2, wantView: 1},
 		{name: "signers=2/Simple___/QC/__/__", tr: S, qc: T, tc: F, ac: F, firstSignerIdx: 2, wantView: 1},
 		{name: "signers=2/Simple___/QC/__/AC", tr: S, qc: T, tc: F, ac: T, firstSignerIdx: 2, wantView: 1},
+		{name: "signers=2/Simple___/QC/TC/__", tr: S, qc: T, tc: T, ac: F, firstSignerIdx: 2, wantView: 1},
 		{name: "signers=2/Simple___/QC/TC/AC", tr: S, qc: T, tc: T, ac: T, firstSignerIdx: 2, wantView: 1},
 		{name: "signers=2/Aggregate/__/__/__", tr: A, qc: F, tc: F, ac: F, firstSignerIdx: 2, wantView: 1}, // empty syncInfo, should not advance view
 		{name: "signers=2/Aggregate/__/__/AC", tr: A, qc: F, tc: F, ac: T, firstSignerIdx: 2, wantView: 1},
@@ -217,6 +222,7 @@ func TestAdvanceView(t *testing.T) {
 		{name: "signers=2/Aggregate/__/TC/AC", tr: A, qc: F, tc: T, ac: T, firstSignerIdx: 2, wantView: 1},
 		{name: "signers=2/Aggregate/QC/__/__", tr: A, qc: T, tc: F, ac: F, firstSignerIdx: 2, wantView: 1},
 		{name: "signers=2/Aggregate/QC/__/AC", tr: A, qc: T, tc: F, ac: T, firstSignerIdx: 2, wantView: 1},
+		{name: "signers=2/Aggregate/QC/TC/__", tr: A, qc: T, tc: T, ac: F, firstSignerIdx: 2, wantView: 1},
 		{name: "signers=2/Aggregate/QC/TC/AC", tr: A, qc: T, tc: T, ac: T, firstSignerIdx: 2, wantView: 1},
 	}
 	for _, tt := range tests {
diff --git a/protocol/synchronizer/timeoutrule_aggregate.go b/protocol/synchronizer/timeoutrule_aggregate.go
index 3d333da1..883f38f3 100644
--- a/protocol/synchronizer/timeoutrule_aggregate.go
+++ b/protocol/synchronizer/timeoutrule_aggregate.go
@@ -62,24 +62,25 @@ func (s *Aggregate) RemoteTimeoutRule(currentView, timeoutView hotstuff.View, ti
 }
 
 func (s *Aggregate) VerifySyncInfo(syncInfo hotstuff.SyncInfo) (qc *hotstuff.QuorumCert, view hotstuff.View, timeout bool, err error) {
+	// get the highest view of the sync info's AggQC and TC
+	view, timeout = syncInfo.HighestViewAggQC()
+
 	if timeoutCert, haveTC := syncInfo.TC(); haveTC {
 		if err := s.auth.VerifyTimeoutCert(timeoutCert); err != nil {
 			return nil, 0, timeout, fmt.Errorf("failed to verify timeout certificate: %w", err)
 		}
-		view = timeoutCert.View()
-		timeout = true
 	}
-
 	if aggQC, haveQC := syncInfo.AggQC(); haveQC {
 		highQC, err := s.auth.VerifyAggregateQC(aggQC)
 		if err != nil {
 			return nil, 0, timeout, fmt.Errorf("failed to verify aggregate quorum certificate: %w", err)
 		}
-		if aggQC.View() >= view {
-			view = aggQC.View()
-			timeout = true
-		}
 		return &highQC, view, timeout, nil
+	} else if qc, haveQC := syncInfo.QC(); haveQC {
+		if err := s.auth.VerifyQuorumCert(qc); err != nil {
+			return nil, 0, timeout, fmt.Errorf("failed to verify quorum certificate: %w", err)
+		}
+		return &qc, view, timeout, nil
 	}
 	return nil, view, timeout, nil // aggregate quorum certificate not present, so no high QC available
 }
diff --git a/protocol/synchronizer/timeoutrule_simple.go b/protocol/synchronizer/timeoutrule_simple.go
index fcc6cb35..e60414ae 100644
--- a/protocol/synchronizer/timeoutrule_simple.go
+++ b/protocol/synchronizer/timeoutrule_simple.go
@@ -47,23 +47,18 @@ func (s *Simple) RemoteTimeoutRule(_, timeoutView hotstuff.View, timeouts []hots
 }
 
 func (s *Simple) VerifySyncInfo(syncInfo hotstuff.SyncInfo) (qc *hotstuff.QuorumCert, view hotstuff.View, timeout bool, err error) {
+	// get the highest view of the sync info's QC and TC
+	view, timeout = syncInfo.HighestView()
+
 	if timeoutCert, haveTC := syncInfo.TC(); haveTC {
 		if err := s.auth.VerifyTimeoutCert(timeoutCert); err != nil {
 			return nil, 0, timeout, fmt.Errorf("failed to verify timeout certificate: %w", err)
 		}
-		view = timeoutCert.View()
-		timeout = true
 	}
-
 	if quorumCert, haveQC := syncInfo.QC(); haveQC {
 		if err := s.auth.VerifyQuorumCert(quorumCert); err != nil {
 			return nil, 0, timeout, fmt.Errorf("failed to verify quorum certificate: %w", err)
 		}
-		// if there is both a TC and a QC, we use the QC if its view is greater or equal to the TC.
-		if quorumCert.View() >= view {
-			view = quorumCert.View()
-			timeout = false
-		}
 		return &quorumCert, view, timeout, nil
 	}
 	return nil, view, timeout, nil // quorum certificate not present, so no high QC available
diff --git a/types.go b/types.go
index e3d78fab..37c894b2 100644
--- a/types.go
+++ b/types.go
@@ -177,6 +177,42 @@ func (si *SyncInfo) SetAggQC(aggQC AggregateQC) {
 	si.aggQC = &aggQC
 }
 
+// HighestView returns the highest view among the QC and TC,
+// and whether it came from a timeout.
+func (si *SyncInfo) HighestView() (view View, timeout bool) {
+	switch {
+	case si.qc != nil && si.tc != nil:
+		if si.qc.View() >= si.tc.View() {
+			return si.qc.View(), false
+		}
+		return si.tc.View(), true
+	case si.qc != nil:
+		return si.qc.View(), false
+	case si.tc != nil:
+		return si.tc.View(), true
+	}
+	// no QC or TC present
+	return 0, false
+}
+
+// HighestViewAggQC returns the highest view among the AggQC and TC,
+// and whether it came from a timeout.
+func (si *SyncInfo) HighestViewAggQC() (view View, timeout bool) {
+	switch {
+	case si.aggQC != nil && si.tc != nil:
+		if si.aggQC.View() >= si.tc.View() {
+			return si.aggQC.View(), true // aggQC is always from timeouts
+		}
+		return si.tc.View(), true
+	case si.aggQC != nil:
+		return si.aggQC.View(), true
+	case si.tc != nil:
+		return si.tc.View(), true
+	}
+	// no AggQC or TC present
+	return 0, false
+}
+
 // QC returns the quorum certificate, if present.
 func (si SyncInfo) QC() (_ QuorumCert, _ bool) {
 	if si.qc != nil {