diff --git a/src/jsontestrunner/main.cpp b/src/jsontestrunner/main.cpp
index 5449299..6e0c004 100644
--- a/src/jsontestrunner/main.cpp
+++ b/src/jsontestrunner/main.cpp
@@ -56,7 +56,7 @@ static JSONCPP_STRING readInputTestFile(const char* path) {
     return JSONCPP_STRING("");
   fseek(file, 0, SEEK_END);
   long const size = ftell(file);
-  unsigned long const usize = static_cast<unsigned long>(size);
+  size_t const usize = static_cast<unsigned long>(size);
   fseek(file, 0, SEEK_SET);
   JSONCPP_STRING text;
   char* buffer = new char[size + 1];
diff --git a/src/lib_json/json_reader.cpp b/src/lib_json/json_reader.cpp
index 077da1b..ce4aac4 100644
--- a/src/lib_json/json_reader.cpp
+++ b/src/lib_json/json_reader.cpp
@@ -577,7 +577,7 @@ bool Reader::decodeNumber(Token& token, Value& decoded) {
     Char c = *current++;
     if (c < '0' || c > '9')
       return decodeDouble(token, decoded);
-    Value::UInt digit(static_cast<Value::UInt>(c - '0'));
+    auto digit(static_cast<Value::UInt>(c - '0'));
     if (value >= threshold) {
       // We've hit or exceeded the max value divided by 10 (rounded down). If
       // a) we've only just touched the limit, b) this is the last digit, and
@@ -1569,7 +1569,7 @@ bool OurReader::decodeNumber(Token& token, Value& decoded) {
     Char c = *current++;
     if (c < '0' || c > '9')
       return decodeDouble(token, decoded);
-    Value::UInt digit(static_cast<Value::UInt>(c - '0'));
+    auto digit(static_cast<Value::UInt>(c - '0'));
     if (value >= threshold) {
       // We've hit or exceeded the max value divided by 10 (rounded down). If
       // a) we've only just touched the limit, b) this is the last digit, and
@@ -1611,7 +1611,7 @@ bool OurReader::decodeDouble(Token& token, Value& decoded) {
   if (length < 0) {
     return addError("Unable to parse token length", token);
   }
-  size_t const ulength = static_cast<size_t>(length);
+  auto const ulength = static_cast<size_t>(length);
 
   // Avoid using a string constant for the format control string given to
   // sscanf, as this can cause hard to debug crashes on OS X. See here for more
diff --git a/src/lib_json/json_value.cpp b/src/lib_json/json_value.cpp
index 5e83239..ef95117 100644
--- a/src/lib_json/json_value.cpp
+++ b/src/lib_json/json_value.cpp
@@ -990,7 +990,7 @@ Value& Value::operator[](ArrayIndex index) {
   if (type_ == nullValue)
     *this = Value(arrayValue);
   CZString key(index);
-  ObjectValues::iterator it = value_.map_->lower_bound(key);
+  auto it = value_.map_->lower_bound(key);
   if (it != value_.map_->end() && (*it).first == key)
     return (*it).second;
 
@@ -1113,7 +1113,7 @@ Value& Value::resolveReference(const char* key) {
     *this = Value(objectValue);
   CZString actualKey(key, static_cast<unsigned>(strlen(key)),
                      CZString::noDuplication); // NOTE!
-  ObjectValues::iterator it = value_.map_->lower_bound(actualKey);
+  auto it = value_.map_->lower_bound(actualKey);
   if (it != value_.map_->end() && (*it).first == actualKey)
     return (*it).second;
 
@@ -1132,7 +1132,7 @@ Value& Value::resolveReference(char const* key, char const* end) {
     *this = Value(objectValue);
   CZString actualKey(key, static_cast<unsigned>(end - key),
                      CZString::duplicateOnCopy);
-  ObjectValues::iterator it = value_.map_->lower_bound(actualKey);
+  auto it = value_.map_->lower_bound(actualKey);
   if (it != value_.map_->end() && (*it).first == actualKey)
     return (*it).second;
 
@@ -1226,7 +1226,7 @@ bool Value::removeMember(const char* begin, const char* end, Value* removed) {
   }
   CZString actualKey(begin, static_cast<unsigned>(end - begin),
                      CZString::noDuplication);
-  ObjectValues::iterator it = value_.map_->find(actualKey);
+  auto it = value_.map_->find(actualKey);
   if (it == value_.map_->end())
     return false;
   if (removed)
@@ -1262,7 +1262,7 @@ bool Value::removeIndex(ArrayIndex index, Value* removed) {
     return false;
   }
   CZString key(index);
-  ObjectValues::iterator it = value_.map_->find(key);
+  auto it = value_.map_->find(key);
   if (it == value_.map_->end()) {
     return false;
   }
@@ -1276,7 +1276,7 @@ bool Value::removeIndex(ArrayIndex index, Value* removed) {
   }
   // erase the last one ("leftover")
   CZString keyLast(oldSize - 1);
-  ObjectValues::iterator itLast = value_.map_->find(keyLast);
+  auto itLast = value_.map_->find(keyLast);
   value_.map_->erase(itLast);
   return true;
 }
@@ -1608,7 +1608,7 @@ Path::Path(const JSONCPP_STRING& path,
 void Path::makePath(const JSONCPP_STRING& path, const InArgs& in) {
   const char* current = path.c_str();
   const char* end = current + path.length();
-  InArgs::const_iterator itInArg = in.begin();
+  auto itInArg = in.begin();
   while (current != end) {
     if (*current == '[') {
       ++current;
diff --git a/src/lib_json/json_writer.cpp b/src/lib_json/json_writer.cpp
index 7138b7a..993001c 100644
--- a/src/lib_json/json_writer.cpp
+++ b/src/lib_json/json_writer.cpp
@@ -147,7 +147,7 @@ JSONCPP_STRING valueToString(double value,
         (precisionType == PrecisionType::significantDigits) ? "%.*g" : "%.*f",
         precision, value);
     assert(len >= 0);
-    size_t wouldPrint = static_cast<size_t>(len);
+    auto wouldPrint = static_cast<size_t>(len);
     if (wouldPrint >= buffer.size()) {
       buffer.resize(wouldPrint + 1);
       continue;
@@ -409,7 +409,7 @@ void FastWriter::writeValue(const Value& value) {
   case objectValue: {
     Value::Members members(value.getMemberNames());
     document_ += '{';
-    for (Value::Members::iterator it = members.begin(); it != members.end();
+    for (auto it = members.begin(); it != members.end();
          ++it) {
       const JSONCPP_STRING& name = *it;
       if (it != members.begin())
@@ -479,7 +479,7 @@ void StyledWriter::writeValue(const Value& value) {
     else {
       writeWithIndent("{");
       indent();
-      Value::Members::iterator it = members.begin();
+      auto it = members.begin();
       for (;;) {
         const JSONCPP_STRING& name = *it;
         const Value& childValue = value[name];
@@ -699,7 +699,7 @@ void StyledStreamWriter::writeValue(const Value& value) {
     else {
       writeWithIndent("{");
       indent();
-      Value::Members::iterator it = members.begin();
+      auto it = members.begin();
       for (;;) {
         const JSONCPP_STRING& name = *it;
         const Value& childValue = value[name];
@@ -979,7 +979,7 @@ void BuiltStyledStreamWriter::writeValue(Value const& value) {
     else {
       writeWithIndent("{");
       indent();
-      Value::Members::iterator it = members.begin();
+      auto it = members.begin();
       for (;;) {
         JSONCPP_STRING const& name = *it;
         Value const& childValue = value[name];
diff --git a/src/test_lib_json/jsontest.cpp b/src/test_lib_json/jsontest.cpp
index f661505..03703c9 100644
--- a/src/test_lib_json/jsontest.cpp
+++ b/src/test_lib_json/jsontest.cpp
@@ -278,7 +278,7 @@ bool Runner::runAllTest(bool printSummary) const {
     }
 
     if (printSummary) {
-      unsigned int failedCount = static_cast<unsigned int>(failures.size());
+      auto failedCount = static_cast<unsigned int>(failures.size());
       unsigned int passedCount = count - failedCount;
       printf("%u/%u tests passed (%u failure(s))\n", passedCount, count,
              failedCount);
diff --git a/src/test_lib_json/main.cpp b/src/test_lib_json/main.cpp
index 8b21547..d0315d7 100644
--- a/src/test_lib_json/main.cpp
+++ b/src/test_lib_json/main.cpp
@@ -1036,7 +1036,7 @@ JSONTEST_FIXTURE(ValueTest, integers) {
       normalizeFloatingPointStr(JsonTest::ToJsonString(val.asString())));
 
   // 10^19
-  const Json::UInt64 ten_to_19 = static_cast<Json::UInt64>(1e19);
+  const auto ten_to_19 = static_cast<Json::UInt64>(1e19);
   val = Json::Value(Json::UInt64(ten_to_19));
 
   JSONTEST_ASSERT_EQUAL(Json::uintValue, val.type());