diff --git a/src/ui/HeaderBar.cpp b/src/ui/HeaderBar.cpp
index 1a2458b..8227016 100644
--- a/src/ui/HeaderBar.cpp
+++ b/src/ui/HeaderBar.cpp
@@ -107,9 +107,9 @@ HeaderBar::~HeaderBar()
     unregisterForEvents();
 }
 
-void HeaderBar::handleEvent(std::shared_ptr<const TickAdvancedEvent> event)
+void HeaderBar::handleEvent(std::shared_ptr<const TickAdvancedEvent> /*event*/)
 {
-    const int totalSeconds = static_cast<int>(ticksToSeconds(event->tick));
+    const int totalSeconds = static_cast<int>(ticksToSeconds(m_sim->getCurrentTick()));
     m_timeLabel->setText(
         QString("%1:%2")
             .arg(totalSeconds / 60, 2, 10, QChar('0'))
@@ -195,22 +195,26 @@ void HeaderBar::handleEvent(std::shared_ptr<const GameSpeedChangedEvent> event)
     }
 }
 
-void HeaderBar::handleEvent(std::shared_ptr<const BossWaveUpdatedEvent> event)
+void HeaderBar::handleEvent(std::shared_ptr<const BossWaveUpdatedEvent> /*event*/)
 {
-    const int bossSeconds = static_cast<int>(
-        ticksToSeconds(event->countdownTicks > 0 ? event->countdownTicks : 0));
+    const Tick countdownTicks = m_sim->getBossCountdownTicks();
+    const int  bossSeconds    = static_cast<int>(
+        ticksToSeconds(countdownTicks > 0 ? countdownTicks : 0));
 	m_bossWaveLabel->setText(
 		tr("Boss Wave #%1")
-		.arg(event->counter));
+		.arg(m_sim->getBossWaveCounter()));
 	m_nextBossLabel->setText(
 		tr("Next boss: %1:%2")
 		.arg(bossSeconds / 60)
 		.arg(bossSeconds % 60, 2, 10, QChar('0')));
 }
 
-void HeaderBar::handleEvent(std::shared_ptr<const ArtifactCountChangedEvent> event)
+void HeaderBar::handleEvent(std::shared_ptr<const ArtifactCountChangedEvent> /*event*/)
 {
-    m_artifactsLabel->setText(tr("Artifacts: %1/%2").arg(event->count).arg(event->winCount));
+    m_artifactsLabel->setText(
+        tr("Artifacts: %1/%2")
+            .arg(m_sim->getArtifactCount())
+            .arg(m_sim->getConfig().world.artifacts.artifactWinCount));
 }
 
 void HeaderBar::onSpeedButton(int index)
diff --git a/src/ui/HeaderBar.h b/src/ui/HeaderBar.h
index 1bc7bea..2bb1f87 100644
--- a/src/ui/HeaderBar.h
+++ b/src/ui/HeaderBar.h
@@ -75,8 +75,8 @@ private:
 
     ItemIconCache*           m_itemIcons;  // Not owned; lives in MainWindow.
 
-    // The simulation is the single source of truth for the block stock and the
-    // expansion cost; the change events are only refresh signals.
+    // The simulation is the single source of truth for everything the header
+    // displays; the change events are only refresh signals.
     const Simulation*        m_sim;
 
     static const double kSpeeds[];