--- a/gfx/layers/apz/src/APZCTreeManager.cpp
+++ b/gfx/layers/apz/src/APZCTreeManager.cpp
@@ -301,16 +301,18 @@ APZCTreeManager::GetFrameTime()
 {
   return TimeStamp::Now();
 }
 
 void
 APZCTreeManager::SetAllowedTouchBehavior(uint64_t aInputBlockId,
                                          const nsTArray<TouchBehaviorFlags> &aValues)
 {
+  APZThreadUtils::AssertOnControllerThread();
+
   mInputQueue->SetAllowedTouchBehavior(aInputBlockId, aValues);
 }
 
 template<class ScrollNode> void // ScrollNode is a LayerMetricsWrapper or a WebRenderScrollDataWrapper
 APZCTreeManager::UpdateHitTestingTreeImpl(uint64_t aRootLayerTreeId,
                                           const ScrollNode& aRoot,
                                           bool aIsFirstPaint,
                                           uint64_t aOriginatingLayersId,
@@ -726,30 +728,34 @@ GetEventRegionsOverride(HitTestingTreeNo
   }
   return result;
 }
 
 void
 APZCTreeManager::StartScrollbarDrag(const ScrollableLayerGuid& aGuid,
                                     const AsyncDragMetrics& aDragMetrics)
 {
+  APZThreadUtils::AssertOnControllerThread();
+
   RefPtr<AsyncPanZoomController> apzc = GetTargetAPZC(aGuid);
   if (!apzc) {
     NotifyScrollbarDragRejected(aGuid);
     return;
   }
 
   uint64_t inputBlockId = aDragMetrics.mDragStartSequenceNumber;
   mInputQueue->ConfirmDragBlock(inputBlockId, apzc, aDragMetrics);
 }
 
 bool
 APZCTreeManager::StartAutoscroll(const ScrollableLayerGuid& aGuid,
                                  const ScreenPoint& aAnchorLocation)
 {
+  APZThreadUtils::AssertOnControllerThread();
+
   RefPtr<AsyncPanZoomController> apzc = GetTargetAPZC(aGuid);
   if (!apzc) {
     if (XRE_IsGPUProcess()) {
       // If we're in the compositor process, the "return false" will be
       // ignored because the query comes over the PAPZCTreeManager protocol
       // via an async message. In this case, send an explicit rejection
       // message to content.
       NotifyAutoscrollRejected(aGuid);
@@ -759,16 +765,18 @@ APZCTreeManager::StartAutoscroll(const S
 
   apzc->StartAutoscroll(aAnchorLocation);
   return true;
 }
 
 void
 APZCTreeManager::StopAutoscroll(const ScrollableLayerGuid& aGuid)
 {
+  APZThreadUtils::AssertOnControllerThread();
+
   if (RefPtr<AsyncPanZoomController> apzc = GetTargetAPZC(aGuid)) {
     apzc->StopAutoscroll();
   }
 }
 
 void
 APZCTreeManager::NotifyScrollbarDragRejected(const ScrollableLayerGuid& aGuid) const
 {