diff --git a/googletest/test/googletest-listener-test.cc b/googletest/test/googletest-listener-test.cc
index 89d01b37..654486d7 100644
--- a/googletest/test/googletest-listener-test.cc
+++ b/googletest/test/googletest-listener-test.cc
@@ -38,13 +38,7 @@
 #include "gtest/internal/custom/gtest.h"
 
 using ::testing::AddGlobalTestEnvironment;
-using ::testing::Environment;
 using ::testing::InitGoogleTest;
-using ::testing::Test;
-using ::testing::TestEventListener;
-using ::testing::TestInfo;
-using ::testing::TestPartResult;
-using ::testing::TestSuite;
 using ::testing::UnitTest;
 
 // Used by tests to register their events.
@@ -278,7 +272,7 @@ int main(int argc, char** argv) {
 
   AddGlobalTestEnvironment(new EnvironmentInvocationCatcher);
 
-  GTEST_CHECK_(events.size() == 0)
+  GTEST_CHECK_(events.empty())
       << "AddGlobalTestEnvironment should not generate any events itself.";
 
   GTEST_FLAG_SET(repeat, 2);
diff --git a/googletest/test/googletest-output-test_.cc b/googletest/test/googletest-output-test_.cc
index 1a496ac8..44d0fc13 100644
--- a/googletest/test/googletest-output-test_.cc
+++ b/googletest/test/googletest-output-test_.cc
@@ -1025,7 +1025,7 @@ int main(int argc, char** argv) {
                  std::string("internal_skip_environment_and_ad_hoc_tests")) > 0;
 
 #ifdef GTEST_HAS_DEATH_TEST
-  if (GTEST_FLAG_GET(internal_run_death_test) != "") {
+  if (!GTEST_FLAG_GET(internal_run_death_test).empty()) {
     // Skip the usual output capturing if we're running as the child
     // process of an threadsafe-style death test.
 #if defined(GTEST_OS_WINDOWS)
diff --git a/googletest/test/googletest-param-test-test.cc b/googletest/test/googletest-param-test-test.cc
index 63db2860..c9c5e78e 100644
--- a/googletest/test/googletest-param-test-test.cc
+++ b/googletest/test/googletest-param-test-test.cc
@@ -221,7 +221,7 @@ class DogAdder {
   }
   DogAdder operator+(const DogAdder& other) const {
     Message msg;
-    msg << value_.c_str() << other.value_.c_str();
+    msg << value_ << other.value_;
     return DogAdder(msg.GetString().c_str());
   }
   bool operator<(const DogAdder& other) const { return value_ < other.value_; }
diff --git a/googletest/test/googletest-printers-test.cc b/googletest/test/googletest-printers-test.cc
index 5fdc0867..401e0463 100644
--- a/googletest/test/googletest-printers-test.cc
+++ b/googletest/test/googletest-printers-test.cc
@@ -266,7 +266,6 @@ using ::std::set;
 using ::std::vector;
 using ::testing::PrintToString;
 using ::testing::internal::FormatForComparisonFailureMessage;
-using ::testing::internal::ImplicitCast_;
 using ::testing::internal::NativeArray;
 using ::testing::internal::RelationToSourceReference;
 using ::testing::internal::Strings;
diff --git a/googletest/test/googletest-shuffle-test_.cc b/googletest/test/googletest-shuffle-test_.cc
index a14e22f9..b570c488 100644
--- a/googletest/test/googletest-shuffle-test_.cc
+++ b/googletest/test/googletest-shuffle-test_.cc
@@ -35,7 +35,6 @@ namespace {
 
 using ::testing::EmptyTestEventListener;
 using ::testing::InitGoogleTest;
-using ::testing::Message;
 using ::testing::Test;
 using ::testing::TestEventListeners;
 using ::testing::TestInfo;
diff --git a/googletest/test/gtest_unittest.cc b/googletest/test/gtest_unittest.cc
index aea8e1f2..768911ab 100644
--- a/googletest/test/gtest_unittest.cc
+++ b/googletest/test/gtest_unittest.cc
@@ -211,7 +211,6 @@ using testing::TestPartResult;
 using testing::TestPartResultArray;
 using testing::TestProperty;
 using testing::TestResult;
-using testing::TestSuite;
 using testing::TimeInMillis;
 using testing::UnitTest;
 using testing::internal::AlwaysFalse;
@@ -227,7 +226,6 @@ using testing::internal::FloatingPoint;
 using testing::internal::ForEach;
 using testing::internal::FormatEpochTimeInMillisAsIso8601;
 using testing::internal::FormatTimeInMillisAsSeconds;
-using testing::internal::GetCurrentOsStackTraceExceptTop;
 using testing::internal::GetElementOr;
 using testing::internal::GetNextRandomSeed;
 using testing::internal::GetRandomSeedFromFlag;
@@ -244,8 +242,6 @@ using testing::internal::IsNotContainer;
 using testing::internal::kMaxRandomSeed;
 using testing::internal::kTestTypeIdInGoogleTest;
 using testing::internal::NativeArray;
-using testing::internal::OsStackTraceGetter;
-using testing::internal::OsStackTraceGetterInterface;
 using testing::internal::ParseFlag;
 using testing::internal::RelationToSourceCopy;
 using testing::internal::RelationToSourceReference;
@@ -259,7 +255,6 @@ using testing::internal::StreamableToString;
 using testing::internal::String;
 using testing::internal::TestEventListenersAccessor;
 using testing::internal::TestResultAccessor;
-using testing::internal::UnitTestImpl;
 using testing::internal::WideStringToUtf8;
 using testing::internal::edit_distance::CalculateOptimalEdits;
 using testing::internal::edit_distance::CreateUnifiedDiff;