diff --git a/test/cpp/qps/timer.cc b/test/cpp/qps/timer.cc
index ff21f1a3778..5a5be97071b 100644
--- a/test/cpp/qps/timer.cc
+++ b/test/cpp/qps/timer.cc
@@ -45,7 +45,7 @@ static double time_double(struct timeval* tv) {
 Timer::Result Timer::Sample() {
   struct rusage usage;
   struct timeval tv;
-  gettimeofday(&tv, NULL);
+  gettimeofday(&tv, nullptr);
   getrusage(RUSAGE_SELF, &usage);
 
   Result r;
@@ -62,4 +62,4 @@ Timer::Result Timer::Mark() {
   r.user = s.user - start_.user;
   r.system = s.system - start_.system;
   return r;
-}
\ No newline at end of file
+}