diff --git a/tests/gtest_main.cpp b/tests/gtest_main.cpp
index dd2dece..b79c8aa 100644
--- a/tests/gtest_main.cpp
+++ b/tests/gtest_main.cpp
@@ -635,7 +635,7 @@
     sigquit_flag = false;
     // Print current running tests.
     printf("List of current running tests:\n");
-    for (auto& child_proc : child_proc_list) {
+    for (const auto& child_proc : child_proc_list) {
       if (child_proc.pid != 0) {
         std::string test_name = testcase_list[child_proc.testcase_id].GetTestName(child_proc.test_id);
         int64_t current_time_ns = NanoTime();
@@ -646,7 +646,7 @@
   } else if (sigint_flag) {
     sigint_flag = false;
     // Kill current running tests.
-    for (auto& child_proc : child_proc_list) {
+    for (const auto& child_proc : child_proc_list) {
       if (child_proc.pid != 0) {
         // Send SIGKILL to ensure the child process can be killed unconditionally.
         kill(child_proc.pid, SIGKILL);
diff --git a/tests/pthread_test.cpp b/tests/pthread_test.cpp
index 1766762..9f887e3 100644
--- a/tests/pthread_test.cpp
+++ b/tests/pthread_test.cpp
@@ -70,7 +70,7 @@
   std::vector<pthread_key_t> keys;
 
   auto scope_guard = make_scope_guard([&keys]{
-    for (auto key : keys) {
+    for (const auto& key : keys) {
       EXPECT_EQ(0, pthread_key_delete(key));
     }
   });
@@ -108,7 +108,7 @@
   }
 
   // Don't leak keys.
-  for (auto key : keys) {
+  for (const auto& key : keys) {
     EXPECT_EQ(0, pthread_key_delete(key));
   }
   keys.clear();
@@ -1162,7 +1162,7 @@
   void* maps_stack_hi = NULL;
   std::vector<map_record> maps;
   ASSERT_TRUE(Maps::parse_maps(&maps));
-  for (auto& map : maps) {
+  for (const auto& map : maps) {
     if (map.pathname == "[stack]") {
       maps_stack_hi = reinterpret_cast<void*>(map.addr_end);
       break;
@@ -1552,8 +1552,8 @@
   }
 
   ~StrictAlignmentAllocator() {
-    for (auto& p : allocated_array) {
-      delete [] p;
+    for (const auto& p : allocated_array) {
+      delete[] p;
     }
   }
 
diff --git a/tests/unistd_test.cpp b/tests/unistd_test.cpp
index 500377c..0a97abc 100644
--- a/tests/unistd_test.cpp
+++ b/tests/unistd_test.cpp
@@ -832,11 +832,10 @@
 }
 
 TEST(unistd, sysconf_SC_NPROCESSORS_ONLN) {
-  std::string s;
-  ASSERT_TRUE(android::base::ReadFileToString("/sys/devices/system/cpu/online", &s));
-  std::vector<std::string> strs = android::base::Split(s, ",");
+  std::string line;
+  ASSERT_TRUE(android::base::ReadFileToString("/sys/devices/system/cpu/online", &line));
   long online_cpus = 0;
-  for (auto& s : strs) {
+  for (const std::string& s : android::base::Split(line, ",")) {
     std::vector<std::string> numbers = android::base::Split(s, "-");
     if (numbers.size() == 1u) {
       online_cpus++;