diff --git a/CMakeLists.txt b/CMakeLists.txt
index c5c75d2..f438f18 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -63,7 +63,7 @@ ENDMACRO(jsoncpp_parse_version)
 #SET( JSONCPP_VERSION_MAJOR X )
 #SET( JSONCPP_VERSION_MINOR Y )
 #SET( JSONCPP_VERSION_PATCH Z )
-SET( JSONCPP_VERSION 1.6.3 )
+SET( JSONCPP_VERSION 1.6.4 )
 jsoncpp_parse_version( ${JSONCPP_VERSION} JSONCPP_VERSION )
 #IF(NOT JSONCPP_VERSION_FOUND)
 #    MESSAGE(FATAL_ERROR "Failed to parse version string properly. Expect X.Y.Z")
@@ -97,10 +97,11 @@ endif( MSVC )
 
 if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
   # using regular Clang or AppleClang
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -Wall -Wshorten-64-to-32")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -Werror -Wall -Wconversion -Wshadow -Wno-sign-conversion")
 elseif ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
   # using GCC
-  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -Wall -Wextra -pedantic")
+  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11 -Werror -Wall -Wconversion -Wshadow -Wextra -pedantic")
+  # not yet ready for -Wsign-conversion
 endif()
 
 IF(JSONCPP_WITH_WARNING_AS_ERROR)
diff --git a/include/json/version.h b/include/json/version.h
index 61081e9..bce0a37 100644
--- a/include/json/version.h
+++ b/include/json/version.h
@@ -3,10 +3,10 @@
 #ifndef JSON_VERSION_H_INCLUDED
 # define JSON_VERSION_H_INCLUDED
 
-# define JSONCPP_VERSION_STRING "1.6.3"
+# define JSONCPP_VERSION_STRING "1.6.4"
 # define JSONCPP_VERSION_MAJOR 1
 # define JSONCPP_VERSION_MINOR 6
-# define JSONCPP_VERSION_PATCH 3
+# define JSONCPP_VERSION_PATCH 4
 # define JSONCPP_VERSION_QUALIFIER
 # define JSONCPP_VERSION_HEXA ((JSONCPP_VERSION_MAJOR << 24) | (JSONCPP_VERSION_MINOR << 16) | (JSONCPP_VERSION_PATCH << 8))
 
diff --git a/src/lib_json/json_tool.h b/src/lib_json/json_tool.h
index f9b61c3..e6d4e92 100644
--- a/src/lib_json/json_tool.h
+++ b/src/lib_json/json_tool.h
@@ -30,8 +30,8 @@ static inline std::string codePointToUTF8(unsigned int cp) {
   } else if (cp <= 0xFFFF) {
     result.resize(3);
     result[2] = static_cast<char>(0x80 | (0x3f & cp));
-    result[1] = 0x80 | static_cast<char>((0x3f & (cp >> 6)));
-    result[0] = 0xE0 | static_cast<char>((0xf & (cp >> 12)));
+    result[1] = static_cast<char>(0x80 | (0x3f & (cp >> 6)));
+    result[0] = static_cast<char>(0xE0 | (0xf & (cp >> 12)));
   } else if (cp <= 0x10FFFF) {
     result.resize(4);
     result[3] = static_cast<char>(0x80 | (0x3f & cp));
@@ -63,7 +63,7 @@ typedef char UIntToStringBuffer[uintToStringBufferSize];
 static inline void uintToString(LargestUInt value, char*& current) {
   *--current = 0;
   do {
-    *--current = char(value % 10) + '0';
+    *--current = static_cast<signed char>(value % 10U + static_cast<unsigned>('0'));
     value /= 10;
   } while (value != 0);
 }
diff --git a/src/lib_json/json_value.cpp b/src/lib_json/json_value.cpp
index cc7d4d3..231089f 100644
--- a/src/lib_json/json_value.cpp
+++ b/src/lib_json/json_value.cpp
@@ -108,7 +108,7 @@ static inline char* duplicateAndPrefixStringValue(
   JSON_ASSERT_MESSAGE(length <= (unsigned)Value::maxInt - sizeof(unsigned) - 1U,
                       "in Json::Value::duplicateAndPrefixStringValue(): "
                       "length too big for prefixing");
-  unsigned actualLength = length + sizeof(unsigned) + 1U;
+  unsigned actualLength = length + static_cast<unsigned>(sizeof(unsigned)) + 1U;
   char* newString = static_cast<char*>(malloc(actualLength));
   if (newString == 0) {
     throwRuntimeError(
@@ -232,14 +232,14 @@ void Value::CommentInfo::setComment(const char* text, size_t len) {
 // Notes: policy_ indicates if the string was allocated when
 // a string is stored.
 
-Value::CZString::CZString(ArrayIndex index) : cstr_(0), index_(index) {}
+Value::CZString::CZString(ArrayIndex aindex) : cstr_(0), index_(aindex) {}
 
-Value::CZString::CZString(char const* str, unsigned length, DuplicationPolicy allocate)
+Value::CZString::CZString(char const* str, unsigned ulength, DuplicationPolicy allocate)
     : cstr_(str)
 {
   // allocate != duplicate
-  storage_.policy_ = allocate;
-  storage_.length_ = length;
+  storage_.policy_ = allocate & 0x3;
+  storage_.length_ = ulength & 0x3FFFFFFF;
 }
 
 Value::CZString::CZString(const CZString& other)
@@ -248,9 +248,9 @@ Value::CZString::CZString(const CZString& other)
                 : other.cstr_)
 {
   storage_.policy_ = (other.cstr_
-                 ? (other.storage_.policy_ == noDuplication
+                 ? (static_cast<DuplicationPolicy>(other.storage_.policy_) == noDuplication
                      ? noDuplication : duplicate)
-                 : other.storage_.policy_);
+                 : static_cast<DuplicationPolicy>(other.storage_.policy_));
   storage_.length_ = other.storage_.length_;
 }
 
@@ -312,9 +312,9 @@ bool Value::CZString::isStaticString() const { return storage_.policy_ == noDupl
  * memset( this, 0, sizeof(Value) )
  * This optimization is used in ValueInternalMap fast allocator.
  */
-Value::Value(ValueType type) {
-  initBasic(type);
-  switch (type) {
+Value::Value(ValueType vtype) {
+  initBasic(vtype);
+  switch (vtype) {
   case nullValue:
     break;
   case intValue:
@@ -478,7 +478,7 @@ void Value::swapPayload(Value& other) {
   std::swap(value_, other.value_);
   int temp2 = allocated_;
   allocated_ = other.allocated_;
-  other.allocated_ = temp2;
+  other.allocated_ = temp2 & 0x1;
 }
 
 void Value::swap(Value& other) {
@@ -606,12 +606,12 @@ const char* Value::asCString() const {
   return this_str;
 }
 
-bool Value::getString(char const** str, char const** end) const {
+bool Value::getString(char const** str, char const** cend) const {
   if (type_ != stringValue) return false;
   if (value_.string_ == 0) return false;
   unsigned length;
   decodePrefixedString(this->allocated_, this->value_.string_, &length, str);
-  *end = *str + length;
+  *cend = *str + length;
   return true;
 }
 
@@ -810,7 +810,8 @@ bool Value::asBool() const {
   case uintValue:
     return value_.uint_ ? true : false;
   case realValue:
-    return value_.real_ ? true : false;
+    // This is kind of strange. Not recommended.
+    return (value_.real_ != 0.0) ? true : false;
   default:
     break;
   }
@@ -960,8 +961,8 @@ const Value& Value::operator[](int index) const {
   return (*this)[ArrayIndex(index)];
 }
 
-void Value::initBasic(ValueType type, bool allocated) {
-  type_ = type;
+void Value::initBasic(ValueType vtype, bool allocated) {
+  type_ = vtype;
   allocated_ = allocated;
   comments_ = 0;
   start_ = 0;
@@ -990,7 +991,7 @@ Value& Value::resolveReference(const char* key) {
 }
 
 // @param key is not null-terminated.
-Value& Value::resolveReference(char const* key, char const* end)
+Value& Value::resolveReference(char const* key, char const* cend)
 {
   JSON_ASSERT_MESSAGE(
       type_ == nullValue || type_ == objectValue,
@@ -998,7 +999,7 @@ Value& Value::resolveReference(char const* key, char const* end)
   if (type_ == nullValue)
     *this = Value(objectValue);
   CZString actualKey(
-      key, static_cast<unsigned>(end-key), CZString::duplicateOnCopy);
+      key, static_cast<unsigned>(cend-key), CZString::duplicateOnCopy);
   ObjectValues::iterator it = value_.map_->lower_bound(actualKey);
   if (it != value_.map_->end() && (*it).first == actualKey)
     return (*it).second;
@@ -1016,13 +1017,13 @@ Value Value::get(ArrayIndex index, const Value& defaultValue) const {
 
 bool Value::isValidIndex(ArrayIndex index) const { return index < size(); }
 
-Value const* Value::find(char const* key, char const* end) const
+Value const* Value::find(char const* key, char const* cend) const
 {
   JSON_ASSERT_MESSAGE(
       type_ == nullValue || type_ == objectValue,
       "in Json::Value::find(key, end, found): requires objectValue or nullValue");
   if (type_ == nullValue) return NULL;
-  CZString actualKey(key, static_cast<unsigned>(end-key), CZString::noDuplication);
+  CZString actualKey(key, static_cast<unsigned>(cend-key), CZString::noDuplication);
   ObjectValues::const_iterator it = value_.map_->find(actualKey);
   if (it == value_.map_->end()) return NULL;
   return &(*it).second;
@@ -1066,9 +1067,9 @@ Value const& Value::operator[](CppTL::ConstString const& key) const
 
 Value& Value::append(const Value& value) { return (*this)[size()] = value; }
 
-Value Value::get(char const* key, char const* end, Value const& defaultValue) const
+Value Value::get(char const* key, char const* cend, Value const& defaultValue) const
 {
-  Value const* found = find(key, end);
+  Value const* found = find(key, cend);
   return !found ? defaultValue : *found;
 }
 Value Value::get(char const* key, Value const& defaultValue) const
@@ -1081,12 +1082,12 @@ Value Value::get(std::string const& key, Value const& defaultValue) const
 }
 
 
-bool Value::removeMember(const char* key, const char* end, Value* removed)
+bool Value::removeMember(const char* key, const char* cend, Value* removed)
 {
   if (type_ != objectValue) {
     return false;
   }
-  CZString actualKey(key, static_cast<unsigned>(end-key), CZString::noDuplication);
+  CZString actualKey(key, static_cast<unsigned>(cend-key), CZString::noDuplication);
   ObjectValues::iterator it = value_.map_->find(actualKey);
   if (it == value_.map_->end())
     return false;
@@ -1131,8 +1132,8 @@ bool Value::removeIndex(ArrayIndex index, Value* removed) {
   ArrayIndex oldSize = size();
   // shift left all items left, into the place of the "removed"
   for (ArrayIndex i = index; i < (oldSize - 1); ++i){
-    CZString key(i);
-    (*value_.map_)[key] = (*this)[i + 1];
+    CZString keey(i);
+    (*value_.map_)[keey] = (*this)[i + 1];
   }
   // erase the last one ("leftover")
   CZString keyLast(oldSize - 1);
@@ -1148,9 +1149,9 @@ Value Value::get(const CppTL::ConstString& key,
 }
 #endif
 
-bool Value::isMember(char const* key, char const* end) const
+bool Value::isMember(char const* key, char const* cend) const
 {
-  Value const* value = find(key, end);
+  Value const* value = find(key, cend);
   return NULL != value;
 }
 bool Value::isMember(char const* key) const
diff --git a/src/lib_json/json_valueiterator.inl b/src/lib_json/json_valueiterator.inl
index d01d3c0..b3bbc35 100644
--- a/src/lib_json/json_valueiterator.inl
+++ b/src/lib_json/json_valueiterator.inl
@@ -93,26 +93,26 @@ UInt ValueIteratorBase::index() const {
 }
 
 std::string ValueIteratorBase::name() const {
-  char const* key;
+  char const* keey;
   char const* end;
-  key = memberName(&end);
-  if (!key) return std::string();
-  return std::string(key, end);
+  keey = memberName(&end);
+  if (!keey) return std::string();
+  return std::string(keey, end);
 }
 
 char const* ValueIteratorBase::memberName() const {
-  const char* name = (*current_).first.data();
-  return name ? name : "";
+  const char* cname = (*current_).first.data();
+  return cname ? cname : "";
 }
 
 char const* ValueIteratorBase::memberName(char const** end) const {
-  const char* name = (*current_).first.data();
-  if (!name) {
+  const char* cname = (*current_).first.data();
+  if (!cname) {
     *end = NULL;
     return NULL;
   }
-  *end = name + (*current_).first.length();
-  return name;
+  *end = cname + (*current_).first.length();
+  return cname;
 }
 
 // //////////////////////////////////////////////////////////////////
diff --git a/version b/version
index 266146b..9edc58b 100644
--- a/version
+++ b/version
@@ -1 +1 @@
-1.6.3
+1.6.4