diff --git a/monitoring/histogram.cc b/monitoring/histogram.cc
index 4449ade64..3fb30e0d7 100644
--- a/monitoring/histogram.cc
+++ b/monitoring/histogram.cc
@@ -9,10 +9,10 @@
 
 #include "monitoring/histogram.h"
 
-#include <math.h>
 #include <stdio.h>
 #include <cassert>
 #include <cinttypes>
+#include <cmath>
 
 #include "port/port.h"
 #include "util/cast_util.h"
@@ -177,7 +177,7 @@ double HistogramStat::StandardDeviation() const {
   double variance =
       static_cast<double>(cur_sum_squares * cur_num - cur_sum * cur_sum) /
       static_cast<double>(cur_num * cur_num);
-  return sqrt(variance);
+  return std::sqrt(variance);
 }
 std::string HistogramStat::ToString() const {
   uint64_t cur_num = num();
diff --git a/tools/db_bench_tool.cc b/tools/db_bench_tool.cc
index 383a12062..f0c447262 100644
--- a/tools/db_bench_tool.cc
+++ b/tools/db_bench_tool.cc
@@ -16,7 +16,6 @@
 #include <unistd.h>
 #endif
 #include <fcntl.h>
-#include <math.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/types.h>