diff --git a/src/google/crash_report.h b/src/google/crash_report.h
index 96ba6f14..ef26b17c 100644
--- a/src/google/crash_report.h
+++ b/src/google/crash_report.h
@@ -32,7 +32,7 @@ using std::string;
 struct CrashReport {
   // An optional id for the report.  This is supplied by the caller
   // and is not used by airbag.
-  u_int64_t report_id;
+  string report_id;
 
   // The time that the report was uploaded (milliseconds since the epoch)
   airbag_time_t report_time;