diff --git a/runtime/trace.cc b/runtime/trace.cc
index 88be23f..3734903 100644
--- a/runtime/trace.cc
+++ b/runtime/trace.cc
@@ -17,6 +17,7 @@
 #include "trace.h"
 
 #include <sys/uio.h>
+#include <unistd.h>
 
 #define ATRACE_TAG ATRACE_TAG_DALVIK
 #include "cutils/trace.h"
@@ -534,6 +535,7 @@
   os << StringPrintf("num-method-calls=%zd\n", num_records);
   os << StringPrintf("clock-call-overhead-nsec=%d\n", clock_overhead_ns_);
   os << StringPrintf("vm=art\n");
+  os << StringPrintf("pid=%d\n", getpid());
   if ((flags_ & kTraceCountAllocs) != 0) {
     os << StringPrintf("alloc-count=%d\n", Runtime::Current()->GetStat(KIND_ALLOCATED_OBJECTS));
     os << StringPrintf("alloc-size=%d\n", Runtime::Current()->GetStat(KIND_ALLOCATED_BYTES));