diff --git a/src/jsontestrunner/main.cpp b/src/jsontestrunner/main.cpp
index 3452c59..df717ff 100644
--- a/src/jsontestrunner/main.cpp
+++ b/src/jsontestrunner/main.cpp
@@ -335,6 +335,7 @@ int main(int argc, const char* argv[]) {
     std::cerr << "Unhandled exception:" << std::endl << e.what() << std::endl;
     return 1;
   }
+  return 0;
 }
 
 #if defined(__GNUC__)
diff --git a/src/lib_json/json_value.cpp b/src/lib_json/json_value.cpp
index 0872ff5..1317501 100644
--- a/src/lib_json/json_value.cpp
+++ b/src/lib_json/json_value.cpp
@@ -52,7 +52,7 @@ template <typename T>
 static std::unique_ptr<T> cloneUnique(const std::unique_ptr<T>& p) {
   std::unique_ptr<T> r;
   if (p) {
-    r = std::unique_ptr<T>(new T(*p));
+    r = std::make_unique<T>(*p);
   }
   return r;
 }
@@ -840,7 +840,6 @@ bool Value::isConvertibleTo(ValueType other) const {
            (type() == realValue && InRange(value_.real_, 0, maxUInt)) ||
            type() == booleanValue || type() == nullValue;
   case realValue:
-    return isNumeric() || type() == booleanValue || type() == nullValue;
   case booleanValue:
     return isNumeric() || type() == booleanValue || type() == nullValue;
   case stringValue:
@@ -1240,7 +1239,7 @@ Value::Members Value::getMemberNames() const {
   ObjectValues::const_iterator it = value_.map_->begin();
   ObjectValues::const_iterator itEnd = value_.map_->end();
   for (; it != itEnd; ++it) {
-    members.push_back(String((*it).first.data(), (*it).first.length()));
+    members.emplace_back(String((*it).first.data(), (*it).first.length()));
   }
   return members;
 }
@@ -1397,7 +1396,7 @@ String Value::Comments::get(CommentPlacement slot) const {
 
 void Value::Comments::set(CommentPlacement slot, String comment) {
   if (!ptr_) {
-    ptr_ = std::unique_ptr<Array>(new Array());
+    ptr_ = std::make_unique<Array>();
   }
   // check comments array boundry.
   if (slot < CommentPlacement::numberOfCommentPlacement) {
@@ -1549,7 +1548,7 @@ void Path::makePath(const String& path, const InArgs& in) {
       const char* beginName = current;
       while (current != end && !strchr("[.", *current))
         ++current;
-      args_.push_back(String(beginName, current));
+      args_.emplace_back(String(beginName, current));
     }
   }
 }
diff --git a/src/lib_json/json_writer.cpp b/src/lib_json/json_writer.cpp
index 8bf02db..bc5ce91 100644
--- a/src/lib_json/json_writer.cpp
+++ b/src/lib_json/json_writer.cpp
@@ -68,7 +68,7 @@
 
 #if !defined(isnan)
 // IEEE standard states that NaN values will not compare to themselves
-#define isnan(x) (x != x)
+#define isnan(x) ((x) != (x))
 #endif
 
 #if !defined(__APPLE__)
@@ -1168,9 +1168,7 @@ StreamWriter* StreamWriterBuilder::newStreamWriter() const {
   const bool emitUTF8 = settings_["emitUTF8"].asBool();
   unsigned int pre = settings_["precision"].asUInt();
   CommentStyle::Enum cs = CommentStyle::All;
-  if (cs_str == "All") {
-    cs = CommentStyle::All;
-  } else if (cs_str == "None") {
+  if (cs_str == "None") {
     cs = CommentStyle::None;
   } else {
     throwRuntimeError("commentStyle must be 'All' or 'None'");
diff --git a/src/test_lib_json/jsontest.cpp b/src/test_lib_json/jsontest.cpp
index 0b7d12b..440be73 100644
--- a/src/test_lib_json/jsontest.cpp
+++ b/src/test_lib_json/jsontest.cpp
@@ -253,7 +253,7 @@ void Runner::runTestAt(size_t index, TestResult& result) const {
 
 bool Runner::runAllTest(bool printSummary) const {
   size_t const count = testCount();
-  std::deque<TestResult> failures;
+  std::vector<TestResult> failures;
   for (size_t index = 0; index < count; ++index) {
     TestResult result;
     runTestAt(index, result);
@@ -408,7 +408,7 @@ Json::String ToJsonString(const char* toConvert) {
   return Json::String(toConvert);
 }
 
-Json::String ToJsonString(Json::String in) { return in; }
+Json::String ToJsonString(const Json::String& in) { return in; }
 
 #if JSONCPP_USING_SECURE_MEMORY
 Json::String ToJsonString(std::string in) {
diff --git a/src/test_lib_json/main.cpp b/src/test_lib_json/main.cpp
index 991c247..9b94e5f 100644
--- a/src/test_lib_json/main.cpp
+++ b/src/test_lib_json/main.cpp
@@ -2732,12 +2732,11 @@ JSONTEST_FIXTURE_LOCAL(StreamWriterTest, escapeTabCharacterWindows) {
 
 struct ReaderTest : JsonTest::TestCase {
   void setStrictMode() {
-    reader = std::unique_ptr<Json::Reader>(
-        new Json::Reader(Json::Features{}.strictMode()));
+    reader = std::make_unique<Json::Reader>(Json::Features{}.strictMode());
   }
 
   void setFeatures(Json::Features& features) {
-    reader = std::unique_ptr<Json::Reader>(new Json::Reader(features));
+    reader = std::make_unique<Json::Reader>(features);
   }
 
   void checkStructuredErrors(