diff --git a/util/benchharness_test.cc b/util/benchharness_test.cc
index 39179c02e235e67bcf27f67183168e47e9f635fb..75ff658929ead0717645d33cf491fe4e077c37a2 100644
--- a/util/benchharness_test.cc
+++ b/util/benchharness_test.cc
@@ -18,42 +18,42 @@ BENCHMARK(insertFrontVector) {
 
 BENCHMARK_RELATIVE(insertBackVector) {
   std::vector<int> v;
-  for (int i = 0; i < 100; i++) {
+  for (size_t i = 0; i < 100; i++) {
     v.insert(v.end(), i);
   }
 }
 
 BENCHMARK_N(insertFrontVector_n, n) {
   std::vector<int> v;
-  for (int i = 0; i < n; i++) {
+  for (size_t i = 0; i < n; i++) {
     v.insert(v.begin(), i);
   }
 }
 
 BENCHMARK_RELATIVE_N(insertBackVector_n, n) {
   std::vector<int> v;
-  for (int i = 0; i < n; i++) {
+  for (size_t i = 0; i < n; i++) {
     v.insert(v.end(), i);
   }
 }
 
 BENCHMARK_N(insertFrontEnd_n, n) {
   std::vector<int> v;
-  for (int i = 0; i < n; i++) {
+  for (size_t i = 0; i < n; i++) {
     v.insert(v.begin(), i);
   }
-  for (int i = 0; i < n; i++) {
+  for (size_t i = 0; i < n; i++) {
     v.insert(v.end(), i);
   }
 }
 
 BENCHMARK_RELATIVE_N(insertFrontEndSuspend_n, n) {
   std::vector<int> v;
-  for (int i = 0; i < n; i++) {
+  for (size_t i = 0; i < n; i++) {
     v.insert(v.begin(), i);
   }
   BENCHMARK_SUSPEND {
-    for (int i = 0; i < n; i++) {
+    for (size_t i = 0; i < n; i++) {
       v.insert(v.end(), i);
     }
   }