diff --git a/src/oatpp-postgresql/Executor.cpp b/src/oatpp-postgresql/Executor.cpp
index 48c1e3e..2f077fb 100644
--- a/src/oatpp-postgresql/Executor.cpp
+++ b/src/oatpp-postgresql/Executor.cpp
@@ -45,7 +45,7 @@ namespace {
 
   class VersionRow : public oatpp::DTO {
 
-    DTO_INIT(VersionRow, DTO);
+    DTO_INIT(VersionRow, DTO)
 
     DTO_FIELD(Int64, version);
 
@@ -90,7 +90,7 @@ Executor::QueryParams::QueryParams(const StringTemplate& queryTemplate,
   paramLengths.resize(count);
   paramFormats.resize(count);
 
-  for(v_uint32 i = 0; i < count; i ++) {
+  for(v_int32 i = 0; i < count; i ++) {
 
     const auto& var = queryTemplate.getTemplateVariables()[i];
     auto it = params.find(var.name);
diff --git a/src/oatpp-postgresql/mapping/Deserializer.cpp b/src/oatpp-postgresql/mapping/Deserializer.cpp
index 8b1cbc9..a29bdcd 100644
--- a/src/oatpp-postgresql/mapping/Deserializer.cpp
+++ b/src/oatpp-postgresql/mapping/Deserializer.cpp
@@ -347,7 +347,8 @@ oatpp::Void Deserializer::deserializeSubArray(const Type* type,
   auto itemType = dispatcher->getItemType();
   auto collection = dispatcher->createObject();
 
-  if(dimension < meta.dimensions.size() - 1) {
+  const v_int32 metaDimensions = meta.dimensions.size() - 1;
+  if(dimension < metaDimensions) {
 
     auto size = meta.dimensions[dimension];
 
@@ -358,7 +359,7 @@ oatpp::Void Deserializer::deserializeSubArray(const Type* type,
 
     return collection;
 
-  } else if(dimension == meta.dimensions.size() - 1) {
+  } else if(dimension == metaDimensions) {
 
     auto size = meta.dimensions[dimension];
 
diff --git a/src/oatpp-postgresql/mapping/Deserializer.hpp b/src/oatpp-postgresql/mapping/Deserializer.hpp
index b3410c3..5be10c2 100644
--- a/src/oatpp-postgresql/mapping/Deserializer.hpp
+++ b/src/oatpp-postgresql/mapping/Deserializer.hpp
@@ -111,7 +111,7 @@ class Deserializer {
   template<typename T>
   static const oatpp::Type* generateMultidimensionalArrayType(const InData& data) {
 
-    if(data.size < sizeof(v_int32)) {
+    if(data.size < static_cast<v_buff_size>(sizeof(v_int32))) {
       return nullptr;
     }
 
diff --git a/src/oatpp-postgresql/mapping/PgArray.cpp b/src/oatpp-postgresql/mapping/PgArray.cpp
index 531d28d..fe59eaf 100644
--- a/src/oatpp-postgresql/mapping/PgArray.cpp
+++ b/src/oatpp-postgresql/mapping/PgArray.cpp
@@ -89,7 +89,7 @@ void ArrayUtils::readArrayHeader(data::stream::InputStream* stream,
 
   dimensions.push_back(arrayHeader.size);
 
-  for(v_uint32 i = 1; i < arrayHeader.ndim; i++) {
+  for(v_int32 i = 1; i < arrayHeader.ndim; i++) {
     stream->readExactSizeDataSimple(&v, sizeof(v_int32));
     dimensions.push_back(ntohl(v));
 
diff --git a/src/oatpp-postgresql/mapping/type/Uuid.cpp b/src/oatpp-postgresql/mapping/type/Uuid.cpp
index 35f6c4c..f01bf85 100644
--- a/src/oatpp-postgresql/mapping/type/Uuid.cpp
+++ b/src/oatpp-postgresql/mapping/type/Uuid.cpp
@@ -41,8 +41,8 @@ UuidObject::UuidObject(const oatpp::String& text) {
   std::memcpy(m_data, stream.getData(), DATA_SIZE);
 }
 
-const p_char8 UuidObject::getData() const {
-  return (const p_char8) m_data;
+const v_char8* UuidObject::getData() const {
+  return static_cast<const v_char8*>(m_data);
 }
 
 v_buff_size UuidObject::getSize() const {
diff --git a/src/oatpp-postgresql/mapping/type/Uuid.hpp b/src/oatpp-postgresql/mapping/type/Uuid.hpp
index c3f91e7..4c0dcc0 100644
--- a/src/oatpp-postgresql/mapping/type/Uuid.hpp
+++ b/src/oatpp-postgresql/mapping/type/Uuid.hpp
@@ -59,7 +59,7 @@ class UuidObject {
    * Get raw data of ObjectId.
    * @return
    */
-  const p_char8 getData() const;
+  const v_char8* getData() const;
 
   /**
    * Get size of ObjectId data.