diff --git a/cmake/compiler-flags.cmake b/cmake/compiler-flags.cmake
index 45c55f0a..de8002e4 100644
--- a/cmake/compiler-flags.cmake
+++ b/cmake/compiler-flags.cmake
@@ -268,7 +268,6 @@ endif (CMAKE_CXX_COMPILER_ID MATCHES GNU)
 # Disable some warnings
 #
 if (CMAKE_CXX_COMPILER_ID MATCHES GNU)
-  add_compiler_flags(4.6 "-Wno-sign-compare")
   add_compiler_flags(4.6 "-Wno-unused-parameter")
 
   add_compiler_flags(9.1 "-Wno-pessimizing-move")
diff --git a/src/oatpp/core/data/buffer/Processor.cpp b/src/oatpp/core/data/buffer/Processor.cpp
index 719aae44..4521f6a5 100644
--- a/src/oatpp/core/data/buffer/Processor.cpp
+++ b/src/oatpp/core/data/buffer/Processor.cpp
@@ -115,7 +115,7 @@ v_int32 ProcessingPipeline::iterate(data::buffer::InlineReadData& dataIn,
     }
 
     data::buffer::InlineReadData* currDataOut = &dataOut;
-    if(i < m_intermediateData.size()) {
+    if(i < static_cast<v_buff_size>(m_intermediateData.size())) {
       currDataOut = &m_intermediateData[i];
     }
 
diff --git a/src/oatpp/core/data/share/MemoryLabel.hpp b/src/oatpp/core/data/share/MemoryLabel.hpp
index d8d8d405..9b054bf2 100644
--- a/src/oatpp/core/data/share/MemoryLabel.hpp
+++ b/src/oatpp/core/data/share/MemoryLabel.hpp
@@ -113,7 +113,7 @@ public:
    * Capture data referenced by memory label to its own memory.
    */
   void captureToOwnMemory() const {
-    if(!m_memoryHandle || m_memoryHandle->data() != reinterpret_cast<const char*>(m_data) || m_memoryHandle->size() != m_size) {
+    if(!m_memoryHandle || m_memoryHandle->data() != reinterpret_cast<const char*>(m_data) || static_cast<v_buff_size>(m_memoryHandle->size()) != m_size) {
       m_memoryHandle = std::make_shared<std::string>(reinterpret_cast<const char*>(m_data), m_size);
       m_data = m_memoryHandle->data();
     }
diff --git a/src/oatpp/core/data/share/StringTemplate.cpp b/src/oatpp/core/data/share/StringTemplate.cpp
index 5c32b2b3..59872cb2 100644
--- a/src/oatpp/core/data/share/StringTemplate.cpp
+++ b/src/oatpp/core/data/share/StringTemplate.cpp
@@ -65,7 +65,7 @@ StringTemplate::StringTemplate(const oatpp::String& text, std::vector<Variable>&
   , m_variables(variables)
 {
   v_buff_size prevPos = 0;
-  for(v_int32 i = 0; i < m_variables.size(); i++) {
+  for(size_t i = 0; i < m_variables.size(); i++) {
     const auto& var = m_variables[i];
 
     if(var.posStart < prevPos) {
diff --git a/src/oatpp/core/utils/ConversionUtils.cpp b/src/oatpp/core/utils/ConversionUtils.cpp
index 8eb845d3..f0315695 100644
--- a/src/oatpp/core/utils/ConversionUtils.cpp
+++ b/src/oatpp/core/utils/ConversionUtils.cpp
@@ -36,7 +36,7 @@ namespace oatpp { namespace utils { namespace conversion {
   v_int32 strToInt32(const oatpp::String& str, bool& success){
     char* end;
     v_int32 result = static_cast<v_int32>(std::strtol(str->data(), &end, 10));
-    success = ((reinterpret_cast<v_buff_size>(end) - reinterpret_cast<v_buff_size>(str->data())) == str->size());
+    success = ((reinterpret_cast<v_buff_size>(end) - reinterpret_cast<v_buff_size>(str->data())) == static_cast<v_buff_size>(str->size()));
     return result;
   }
 
@@ -48,7 +48,7 @@ namespace oatpp { namespace utils { namespace conversion {
   v_uint32 strToUInt32(const oatpp::String& str, bool& success){
     char* end;
     v_uint32 result = static_cast<v_uint32>(std::strtoul(str->data(), &end, 10));
-    success = ((reinterpret_cast<v_buff_size>(end) - reinterpret_cast<v_buff_size>(str->data())) == str->size());
+    success = ((reinterpret_cast<v_buff_size>(end) - reinterpret_cast<v_buff_size>(str->data())) == static_cast<v_buff_size>(str->size()));
     return result;
   }
   
@@ -60,7 +60,7 @@ namespace oatpp { namespace utils { namespace conversion {
   v_int64 strToInt64(const oatpp::String& str, bool& success){
     char* end;
     v_int64 result = std::strtoll(str->data(), &end, 10);
-    success = ((reinterpret_cast<v_buff_size>(end) - reinterpret_cast<v_buff_size>(str->data())) == str->size());
+    success = ((reinterpret_cast<v_buff_size>(end) - reinterpret_cast<v_buff_size>(str->data())) == static_cast<v_buff_size>(str->size()));
     return result;
   }
 
@@ -72,7 +72,7 @@ namespace oatpp { namespace utils { namespace conversion {
   v_uint64 strToUInt64(const oatpp::String& str, bool& success){
     char* end;
     v_uint64 result = std::strtoull(str->data(), &end, 10);
-    success = ((reinterpret_cast<v_buff_size>(end) - reinterpret_cast<v_buff_size>(str->data())) == str->size());
+    success = ((reinterpret_cast<v_buff_size>(end) - reinterpret_cast<v_buff_size>(str->data())) == static_cast<v_buff_size>(str->size()));
     return result;
   }
 
@@ -172,7 +172,7 @@ namespace oatpp { namespace utils { namespace conversion {
   v_float32 strToFloat32(const oatpp::String& str, bool& success) {
     char* end;
     v_float32 result = std::strtof(str->data(), &end);
-    success = ((reinterpret_cast<v_buff_size>(end) - reinterpret_cast<v_buff_size>(str->data())) == str->size());
+    success = ((reinterpret_cast<v_buff_size>(end) - reinterpret_cast<v_buff_size>(str->data())) == static_cast<v_buff_size>(str->size()));
     return result;
   }
   
@@ -184,7 +184,7 @@ namespace oatpp { namespace utils { namespace conversion {
   v_float64 strToFloat64(const oatpp::String& str, bool& success) {
     char* end;
     v_float64 result = std::strtod(str->data(), &end);
-    success = ((reinterpret_cast<v_buff_size>(end) - reinterpret_cast<v_buff_size>(str->data())) == str->size());
+    success = ((reinterpret_cast<v_buff_size>(end) - reinterpret_cast<v_buff_size>(str->data())) == static_cast<v_buff_size>(str->size()));
     return result;
   }
 
diff --git a/src/oatpp/web/protocol/http/incoming/SimpleBodyDecoder.cpp b/src/oatpp/web/protocol/http/incoming/SimpleBodyDecoder.cpp
index 0d55f070..2c3fa2bb 100644
--- a/src/oatpp/web/protocol/http/incoming/SimpleBodyDecoder.cpp
+++ b/src/oatpp/web/protocol/http/incoming/SimpleBodyDecoder.cpp
@@ -84,7 +84,7 @@ void SimpleBodyDecoder::handleExpectHeader(const Headers& headers, data::stream:
   auto expect = headers.getAsMemoryLabel<data::share::StringKeyLabelCI>(Header::EXPECT);
   if(expect == Header::Value::EXPECT_100_CONTINUE) {
     auto res = connection->writeExactSizeDataSimple(RESPONSE_100_CONTINUE.data(), RESPONSE_100_CONTINUE.size());
-    if(res != RESPONSE_100_CONTINUE.size()) {
+    if(res != static_cast<v_io_size>(RESPONSE_100_CONTINUE.size())) {
       throw std::runtime_error("[oatpp::web::protocol::http::incoming::SimpleBodyDecoder::handleExpectHeader()]: "
                                "Error. Unable to send 100-continue response.");
     }
diff --git a/test/oatpp/core/data/resource/InMemoryDataTest.cpp b/test/oatpp/core/data/resource/InMemoryDataTest.cpp
index 648f8b45..07df7325 100644
--- a/test/oatpp/core/data/resource/InMemoryDataTest.cpp
+++ b/test/oatpp/core/data/resource/InMemoryDataTest.cpp
@@ -47,7 +47,7 @@ void InMemoryDataTest::onRun() {
       s->writeExactSizeDataSimple(testData->data(), testData->size());
     }
 
-    OATPP_ASSERT(data.getKnownSize() == testData->size())
+    OATPP_ASSERT(data.getKnownSize() == static_cast<v_int64>(testData->size()))
     OATPP_ASSERT(data.getInMemoryData() == testData)
     OATPP_ASSERT(data.getLocation() == nullptr)
   }
diff --git a/test/oatpp/core/data/share/LazyStringMapTest.cpp b/test/oatpp/core/data/share/LazyStringMapTest.cpp
index 47238a12..6974e4ce 100644
--- a/test/oatpp/core/data/share/LazyStringMapTest.cpp
+++ b/test/oatpp/core/data/share/LazyStringMapTest.cpp
@@ -70,8 +70,8 @@ void LazyStringMapTest::onRun() {
     auto s13 = all["key1"];
     auto s23 = all["key2"];
 
-    OATPP_ASSERT(s13.getData() == s1->data() && s13.getSize() == s1->size());
-    OATPP_ASSERT(s23.getData() == s2->data() && s23.getSize() == s2->size());
+    OATPP_ASSERT(s13.getData() == s1->data() && s13.getSize() == static_cast<v_buff_size>(s1->size()));
+    OATPP_ASSERT(s23.getData() == s2->data() && s23.getSize() == static_cast<v_buff_size>(s2->size()));
     OATPP_ASSERT(s1.get() == s13.getMemoryHandle().get());
     OATPP_ASSERT(s2.get() == s23.getMemoryHandle().get());
 
diff --git a/test/oatpp/core/data/stream/BufferStreamTest.cpp b/test/oatpp/core/data/stream/BufferStreamTest.cpp
index b98bc9a4..217da1dc 100644
--- a/test/oatpp/core/data/stream/BufferStreamTest.cpp
+++ b/test/oatpp/core/data/stream/BufferStreamTest.cpp
@@ -111,10 +111,10 @@ void BufferStreamTest::onRun() {
 
     auto wholeText = stream.toString();
 
-    OATPP_ASSERT(wholeText->size() == fragmentsCount * 10);
+    OATPP_ASSERT(wholeText->size() == static_cast<size_t>(fragmentsCount * 10));
 
-    v_int32 substringSize = 10;
-    for(v_int32 i = 0; i < wholeText->size() - substringSize; i ++) {
+    v_buff_size substringSize = 10;
+    for(v_buff_size i = 0; i < static_cast<v_buff_size>(wholeText->size()) - substringSize; i ++) {
       OATPP_ASSERT(oatpp::String(&wholeText->data()[i], substringSize) == stream.getSubstring(i, substringSize));
     }
 
diff --git a/test/oatpp/network/virtual_/InterfaceTest.cpp b/test/oatpp/network/virtual_/InterfaceTest.cpp
index 7504c6fb..f8b19d96 100644
--- a/test/oatpp/network/virtual_/InterfaceTest.cpp
+++ b/test/oatpp/network/virtual_/InterfaceTest.cpp
@@ -56,7 +56,7 @@ namespace {
       auto socket = submission->getSocket();
       
       auto res = socket->writeExactSizeDataSimple(m_dataSample->data(), m_dataSample->size());
-      OATPP_ASSERT(res == m_dataSample->size());
+      OATPP_ASSERT(res == static_cast<v_io_size>(m_dataSample->size()));
       
       v_char8 buffer[100];
       oatpp::data::stream::BufferOutputStream stream;
@@ -89,7 +89,7 @@ namespace {
       oatpp::data::stream::BufferOutputStream stream;
       auto res = oatpp::data::stream::transfer(m_socket.get(), &stream, m_dataSample->size(), buffer, 100);
       
-      OATPP_ASSERT(res == m_dataSample->size());
+      OATPP_ASSERT(res == static_cast<v_io_size>(m_dataSample->size()));
       OATPP_ASSERT(stream.getCurrentPosition() == res);
       OATPP_ASSERT(stream.toString() == m_dataSample);
       
diff --git a/test/oatpp/web/mime/multipart/StatefulParserTest.cpp b/test/oatpp/web/mime/multipart/StatefulParserTest.cpp
index d0805a2f..c553e33c 100644
--- a/test/oatpp/web/mime/multipart/StatefulParserTest.cpp
+++ b/test/oatpp/web/mime/multipart/StatefulParserTest.cpp
@@ -112,17 +112,17 @@ void StatefulParserTest::onRun() {
 
   oatpp::String text = TEST_DATA_1;
 
-  for(v_int32 i = 1; i < text->size(); i++) {
+  for(size_t i = 1; i < text->size(); i++) {
 
     oatpp::web::mime::multipart::PartList multipart("12345");
 
     auto listener = std::make_shared<oatpp::web::mime::multipart::PartsParser>(&multipart);
     listener->setDefaultPartReader(oatpp::web::mime::multipart::createInMemoryPartReader(128));
 
-    parseStepByStep(text, "12345", listener, i);
+    parseStepByStep(text, "12345", listener, static_cast<v_int32>(i));
 
     if(multipart.count() != 5) {
-      OATPP_LOGD(TAG, "TEST_DATA_1 itearation %d", i);
+      OATPP_LOGD(TAG, "TEST_DATA_1 itearation %lu", i);
     }
 
     OATPP_ASSERT(multipart.count() == 5);
diff --git a/test/oatpp/web/protocol/http/encoding/ChunkedTest.cpp b/test/oatpp/web/protocol/http/encoding/ChunkedTest.cpp
index d7294625..5c19da9e 100644
--- a/test/oatpp/web/protocol/http/encoding/ChunkedTest.cpp
+++ b/test/oatpp/web/protocol/http/encoding/ChunkedTest.cpp
@@ -62,7 +62,7 @@ void ChunkedTest::onRun() {
 
     auto count = oatpp::data::stream::transfer(&inStream, &outStream, 0, buffer, bufferSize, &decoder);
     decoded = outStream.toString();
-    OATPP_ASSERT(count == encoded->size());
+    OATPP_ASSERT(count == static_cast<v_io_size>(encoded->size()));
     OATPP_ASSERT(decoded == "");
   }
 
@@ -78,7 +78,7 @@ void ChunkedTest::onRun() {
     auto count = oatpp::data::stream::transfer(&inStream, &outStream, 0, buffer, bufferSize, &encoder);
     encoded = outStream.toString();
 
-    OATPP_ASSERT(count == data->size());
+    OATPP_ASSERT(count == static_cast<v_io_size>(data->size()));
     OATPP_ASSERT(encoded == "5\r\nHello\r\n5\r\n Worl\r\n4\r\nd!!!\r\n0\r\n\r\n");
   }
 
@@ -93,7 +93,7 @@ void ChunkedTest::onRun() {
 
     auto count = oatpp::data::stream::transfer(&inStream, &outStream, 0, buffer, bufferSize, &decoder);
     decoded = outStream.toString();
-    OATPP_ASSERT(count == encoded->size());
+    OATPP_ASSERT(count == static_cast<v_io_size>(encoded->size()));
     OATPP_LOGD(TAG, "decoded='%s'", decoded->c_str());
     OATPP_ASSERT(decoded == data);
   }
@@ -114,7 +114,7 @@ void ChunkedTest::onRun() {
 
     auto count = oatpp::data::stream::transfer(&inStream, &outStream, 0, buffer, bufferSize, &pipeline);
     auto result = outStream.toString();
-    OATPP_ASSERT(count == data->size());
+    OATPP_ASSERT(count == static_cast<v_io_size>(data->size()));
     OATPP_LOGD(TAG, "result='%s'", result->c_str());
     OATPP_ASSERT(result == data);
   }
@@ -122,4 +122,4 @@ void ChunkedTest::onRun() {
 
 }
 
-}}}}}}
\ No newline at end of file
+}}}}}}