diff --git a/libs/gui/VsyncEventData.cpp b/libs/gui/VsyncEventData.cpp
index 76c60c2..91fc9c0 100644
--- a/libs/gui/VsyncEventData.cpp
+++ b/libs/gui/VsyncEventData.cpp
@@ -46,11 +46,15 @@
 
     SAFE_PARCEL(parcel->readInt64, &vsync.frameInterval);
 
-    uint64_t uintPreferredFrameTimelineIndex;
-    SAFE_PARCEL(parcel->readUint64, &uintPreferredFrameTimelineIndex);
+    uint32_t uintPreferredFrameTimelineIndex;
+    SAFE_PARCEL(parcel->readUint32, &uintPreferredFrameTimelineIndex);
     vsync.preferredFrameTimelineIndex = static_cast<size_t>(uintPreferredFrameTimelineIndex);
 
-    for (int i = 0; i < VsyncEventData::kFrameTimelinesLength; i++) {
+    uint32_t uintFrameTimelinesLength;
+    SAFE_PARCEL(parcel->readUint32, &uintFrameTimelinesLength);
+    vsync.frameTimelinesLength = static_cast<size_t>(uintFrameTimelinesLength);
+
+    for (size_t i = 0; i < vsync.frameTimelinesLength; i++) {
         SAFE_PARCEL(parcel->readInt64, &vsync.frameTimelines[i].vsyncId);
         SAFE_PARCEL(parcel->readInt64, &vsync.frameTimelines[i].deadlineTimestamp);
         SAFE_PARCEL(parcel->readInt64, &vsync.frameTimelines[i].expectedPresentationTime);
@@ -60,8 +64,9 @@
 }
 status_t ParcelableVsyncEventData::writeToParcel(Parcel* parcel) const {
     SAFE_PARCEL(parcel->writeInt64, vsync.frameInterval);
-    SAFE_PARCEL(parcel->writeUint64, vsync.preferredFrameTimelineIndex);
-    for (int i = 0; i < VsyncEventData::kFrameTimelinesLength; i++) {
+    SAFE_PARCEL(parcel->writeUint32, vsync.preferredFrameTimelineIndex);
+    SAFE_PARCEL(parcel->writeUint32, vsync.frameTimelinesLength);
+    for (size_t i = 0; i < vsync.frameTimelinesLength; i++) {
         SAFE_PARCEL(parcel->writeInt64, vsync.frameTimelines[i].vsyncId);
         SAFE_PARCEL(parcel->writeInt64, vsync.frameTimelines[i].deadlineTimestamp);
         SAFE_PARCEL(parcel->writeInt64, vsync.frameTimelines[i].expectedPresentationTime);
diff --git a/libs/gui/include/gui/VsyncEventData.h b/libs/gui/include/gui/VsyncEventData.h
index dfdae21..9ddb7cd 100644
--- a/libs/gui/include/gui/VsyncEventData.h
+++ b/libs/gui/include/gui/VsyncEventData.h
@@ -24,7 +24,7 @@
 // Plain Old Data (POD) vsync data structure. For example, it can be easily used in the
 // DisplayEventReceiver::Event union.
 struct VsyncEventData {
-    // Max amount of frame timelines is arbitrarily set to be reasonable.
+    // Max capacity of frame timelines is arbitrarily set to be reasonable.
     static constexpr int64_t kFrameTimelinesLength = 7;
 
     // The current frame interval in ns when this frame was scheduled.
@@ -33,6 +33,9 @@
     // Index into the frameTimelines that represents the platform's preferred frame timeline.
     uint32_t preferredFrameTimelineIndex;
 
+    // Size of frame timelines provided by the platform; max is kFrameTimelinesLength.
+    uint32_t frameTimelinesLength;
+
     struct alignas(8) FrameTimeline {
         // The Vsync Id corresponsing to this vsync event. This will be used to
         // populate ISurfaceComposer::setFrameTimelineVsync and
diff --git a/libs/gui/tests/DisplayEventStructLayout_test.cpp b/libs/gui/tests/DisplayEventStructLayout_test.cpp
index da88463..b7b4ab6 100644
--- a/libs/gui/tests/DisplayEventStructLayout_test.cpp
+++ b/libs/gui/tests/DisplayEventStructLayout_test.cpp
@@ -35,6 +35,7 @@
     CHECK_OFFSET(DisplayEventReceiver::Event::VSync, count, 0);
     CHECK_OFFSET(DisplayEventReceiver::Event::VSync, vsyncData.frameInterval, 8);
     CHECK_OFFSET(DisplayEventReceiver::Event::VSync, vsyncData.preferredFrameTimelineIndex, 16);
+    CHECK_OFFSET(DisplayEventReceiver::Event::VSync, vsyncData.frameTimelinesLength, 20);
     CHECK_OFFSET(DisplayEventReceiver::Event::VSync, vsyncData.frameTimelines, 24);
     CHECK_OFFSET(DisplayEventReceiver::Event::VSync, vsyncData.frameTimelines[0].vsyncId, 24);
     CHECK_OFFSET(DisplayEventReceiver::Event::VSync, vsyncData.frameTimelines[0].deadlineTimestamp,
diff --git a/libs/gui/tests/VsyncEventData_test.cpp b/libs/gui/tests/VsyncEventData_test.cpp
index f114522..6e039ee 100644
--- a/libs/gui/tests/VsyncEventData_test.cpp
+++ b/libs/gui/tests/VsyncEventData_test.cpp
@@ -36,6 +36,7 @@
     FrameTimeline timeline1 = FrameTimeline{4, 5, 6};
     data.vsync.frameTimelines[0] = timeline0;
     data.vsync.frameTimelines[1] = timeline1;
+    data.vsync.frameTimelinesLength = 2;
 
     Parcel p;
     data.writeToParcel(&p);
@@ -45,6 +46,7 @@
     data2.readFromParcel(&p);
     ASSERT_EQ(data.vsync.frameInterval, data2.vsync.frameInterval);
     ASSERT_EQ(data.vsync.preferredFrameTimelineIndex, data2.vsync.preferredFrameTimelineIndex);
+    ASSERT_EQ(data.vsync.frameTimelinesLength, data2.vsync.frameTimelinesLength);
     for (int i = 0; i < VsyncEventData::kFrameTimelinesLength; i++) {
         ASSERT_EQ(data.vsync.frameTimelines[i].vsyncId, data2.vsync.frameTimelines[i].vsyncId);
         ASSERT_EQ(data.vsync.frameTimelines[i].deadlineTimestamp,