Index: lib/xray/xray_fdr_controller.h
===================================================================
--- lib/xray/xray_fdr_controller.h
+++ lib/xray/xray_fdr_controller.h
@@ -327,7 +327,7 @@
     LatestTSC = 0;
     UndoableFunctionEnters = 0;
     UndoableTailExits = 0;
-    return W.writeCustomEvent(TSC, Event, EventSize);
+    return W.writeCustomEvent(TSC, CPU, Event, EventSize);
   }
 
   bool typedEvent(uint64_t TSC, uint16_t CPU, uint16_t EventType,
Index: lib/xray/xray_fdr_log_writer.h
===================================================================
--- lib/xray/xray_fdr_log_writer.h
+++ lib/xray/xray_fdr_log_writer.h
@@ -110,9 +110,10 @@
     return true;
   }
 
-  bool writeCustomEvent(uint64_t TSC, const void *Event, int32_t EventSize) {
+  bool writeCustomEvent(uint64_t TSC, uint16_t CPU, const void *Event,
+                        int32_t EventSize) {
     writeMetadata<MetadataRecord::RecordKinds::CustomEventMarker>(EventSize,
-                                                                  TSC);
+                                                                  TSC, CPU);
     internal_memcpy(NextRecord, Event, EventSize);
     NextRecord += EventSize;
     atomic_fetch_add(&Buffer.Extents, EventSize, memory_order_acq_rel);
Index: lib/xray/xray_fdr_logging.cc
===================================================================
--- lib/xray/xray_fdr_logging.cc
+++ lib/xray/xray_fdr_logging.cc
@@ -148,7 +148,8 @@
     // Version 2 of the log writes the extents of the buffer, instead of
     // relying on an end-of-buffer record.
     // Version 3 includes PID metadata record
-    H.Version = 3;
+    // Version 4 includes CPU data in the custom event records
+    H.Version = 4;
     H.Type = FileTypes::FDR_LOG;
 
     // Test for required CPU features and cache the cycle frequency