diff --git a/.cspell.json b/.cspell.json
index 91c94d92359..80684b9bb81 100644
--- a/.cspell.json
+++ b/.cspell.json
@@ -148,6 +148,8 @@
     "gnustl",
     "libgnustl",
     "Wmissing",
+    "Wmaybe",
+    "Wuninitialized",
     // Android NDK
     "JNIEXPORT",
     "jint",
diff --git a/cmake/compiler_settings.cmake b/cmake/compiler_settings.cmake
index c0c19e5b8da..41fcf937859 100644
--- a/cmake/compiler_settings.cmake
+++ b/cmake/compiler_settings.cmake
@@ -11,6 +11,9 @@ else()
         set(COMPILER_CLANG 1)
     else()
         set(COMPILER_GCC 1)
+        if(MINGW)
+            set(COMPILER_MINGW 1)
+        endif()
     endif()
     set(USE_GCC_FLAGS 1)
 endif()
@@ -34,6 +37,9 @@ endfunction()
 
 macro(set_gcc_flags)
     list(APPEND AWS_COMPILER_FLAGS "-fno-exceptions" "-std=c++${CPP_STANDARD}")
+    if(COMPILER_IS_MINGW)
+        list(APPEND AWS_COMPILER_FLAGS -D__USE_MINGW_ANSI_STDIO=1)
+    endif()
 
     if(NOT BUILD_SHARED_LIBS)
         list(APPEND AWS_COMPILER_FLAGS "-fPIC")
diff --git a/src/aws-cpp-sdk-core/include/aws/core/utils/event/EventHeader.h b/src/aws-cpp-sdk-core/include/aws/core/utils/event/EventHeader.h
index 19199ac462f..c9fffc2b7a2 100644
--- a/src/aws-cpp-sdk-core/include/aws/core/utils/event/EventHeader.h
+++ b/src/aws-cpp-sdk-core/include/aws/core/utils/event/EventHeader.h
@@ -16,6 +16,12 @@
 #include <aws/event-stream/event_stream.h>
 #include <cassert>
 
+#ifdef __MINGW32__
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wmaybe-uninitialized"
+#pragma GCC diagnostic ignored "-Wuninitialized"
+#endif
+
 namespace Aws
 {
     namespace Utils
@@ -350,3 +356,7 @@ namespace Aws
         }
     }
 }
+
+#ifdef __MINGW32__
+#pragma GCC diagnostic pop
+#endif
diff --git a/src/aws-cpp-sdk-core/source/http/windows/WinHttpSyncHttpClient.cpp b/src/aws-cpp-sdk-core/source/http/windows/WinHttpSyncHttpClient.cpp
index c18b78b52ff..eeae903740a 100644
--- a/src/aws-cpp-sdk-core/source/http/windows/WinHttpSyncHttpClient.cpp
+++ b/src/aws-cpp-sdk-core/source/http/windows/WinHttpSyncHttpClient.cpp
@@ -17,7 +17,7 @@
 #include <aws/core/utils/ratelimiter/RateLimiterInterface.h>
 #include <aws/core/utils/UnreferencedParam.h>
 
-#include <Windows.h>
+#include <winsock2.h>
 #include <winhttp.h>
 #include <mstcpip.h> // for tcp_keepalive
 #include <sstream>
@@ -696,7 +696,7 @@ bool WinHttpSyncHttpClient::DoQueryHeaders(void* hHttpRequest, std::shared_ptr<H
     wmemset(contentTypeStr, 0, static_cast<size_t>(dwSize / sizeof(wchar_t)));
 
     WinHttpQueryHeaders(hHttpRequest, WINHTTP_QUERY_CONTENT_TYPE, nullptr, &contentTypeStr, &dwSize, 0);
-    if (contentTypeStr[0] != NULL)
+    if (contentTypeStr[0])
     {
         Aws::String contentStr = StringUtils::FromWString(contentTypeStr);
         response->SetContentType(contentStr);
@@ -727,7 +727,7 @@ bool WinHttpSyncHttpClient::DoQueryHeaders(void* hHttpRequest, std::shared_ptr<H
 
 bool WinHttpSyncHttpClient::DoSendRequest(void* hHttpRequest) const
 {
-    bool success = WinHttpSendRequest(hHttpRequest, NULL, NULL, 0, 0, 0, NULL) != 0;
+    bool success = WinHttpSendRequest(hHttpRequest, NULL, 0, NULL, 0, 0, 0) != 0;
     if (!success)
     {
         AzWinHttpLogLastError("WinHttpSendRequest");
diff --git a/src/aws-cpp-sdk-core/source/http/windows/WinINetSyncHttpClient.cpp b/src/aws-cpp-sdk-core/source/http/windows/WinINetSyncHttpClient.cpp
index caf9e4b423a..baee6054627 100644
--- a/src/aws-cpp-sdk-core/source/http/windows/WinINetSyncHttpClient.cpp
+++ b/src/aws-cpp-sdk-core/source/http/windows/WinINetSyncHttpClient.cpp
@@ -227,7 +227,7 @@ bool WinINetSyncHttpClient::DoQueryHeaders(void* hHttpRequest, std::shared_ptr<H
     char contentTypeStr[1024];
     dwSize = sizeof(contentTypeStr);
     HttpQueryInfoA(hHttpRequest, HTTP_QUERY_CONTENT_TYPE, &contentTypeStr, &dwSize, 0);
-    if (contentTypeStr[0] != NULL)
+    if (contentTypeStr[0])
     {
         response->SetContentType(contentTypeStr);
         AWS_LOGSTREAM_DEBUG(GetLogTag(), "Received content type " << contentTypeStr);
diff --git a/src/aws-cpp-sdk-core/source/platform/windows/FileSystem.cpp b/src/aws-cpp-sdk-core/source/platform/windows/FileSystem.cpp
index b6678e1cc9c..4a799f619ce 100644
--- a/src/aws-cpp-sdk-core/source/platform/windows/FileSystem.cpp
+++ b/src/aws-cpp-sdk-core/source/platform/windows/FileSystem.cpp
@@ -12,7 +12,9 @@
 #include <iostream>
 #include <Userenv.h>
 
-#pragma warning( disable : 4996)
+#ifdef _MSC_VER
+#pragma warning(disable: 4996)
+#endif
 
 using namespace Aws::Utils;
 namespace Aws
@@ -311,6 +313,9 @@ Aws::String CreateTempFilePath()
 {
 #ifdef _MSC_VER
 #pragma warning(disable: 4996) // _CRT_SECURE_NO_WARNINGS
+#elif !defined(L_tmpnam_s)
+    // Definition from the MSVC stdio.h
+    #define L_tmpnam_s (sizeof("\\") + 16)
 #endif
     char s_tempName[L_tmpnam_s+1];
 
diff --git a/src/aws-cpp-sdk-core/source/platform/windows/OSVersionInfo.cpp b/src/aws-cpp-sdk-core/source/platform/windows/OSVersionInfo.cpp
index e2c4a017f0a..c849fbc993a 100644
--- a/src/aws-cpp-sdk-core/source/platform/windows/OSVersionInfo.cpp
+++ b/src/aws-cpp-sdk-core/source/platform/windows/OSVersionInfo.cpp
@@ -9,7 +9,9 @@
 
 #include <iomanip>
 
+#ifdef _MSC_VER
 #pragma warning(disable: 4996)
+#endif
 #include <windows.h>
 #include <stdio.h>
 namespace Aws
diff --git a/src/aws-cpp-sdk-core/source/utils/crypto/factory/Factories.cpp b/src/aws-cpp-sdk-core/source/utils/crypto/factory/Factories.cpp
index 33f562c3608..46bd1f1e9a9 100644
--- a/src/aws-cpp-sdk-core/source/utils/crypto/factory/Factories.cpp
+++ b/src/aws-cpp-sdk-core/source/utils/crypto/factory/Factories.cpp
@@ -809,7 +809,7 @@ std::shared_ptr<Aws::Utils::Crypto::HMAC> Aws::Utils::Crypto::CreateSha256HMACIm
     return GetSha256HMACFactory()->CreateImplementation();
 }
 
-#ifdef _WIN32
+#ifdef _MSC_VER
 #pragma warning( push )
 #pragma warning( disable : 4702 )
 #endif
@@ -902,7 +902,7 @@ std::shared_ptr<SymmetricCipher> Aws::Utils::Crypto::CreateAES_KeyWrapImplementa
     return GetAES_KeyWrapFactory()->CreateImplementation(key);
 }
 
-#ifdef _WIN32
+#ifdef _MSC_VER
 #pragma warning(pop)
 #endif
 
diff --git a/tests/aws-cpp-sdk-s3-integration-tests/BucketAndObjectOperationTest.cpp b/tests/aws-cpp-sdk-s3-integration-tests/BucketAndObjectOperationTest.cpp
index 1c80649d2c1..1f13967b7fb 100644
--- a/tests/aws-cpp-sdk-s3-integration-tests/BucketAndObjectOperationTest.cpp
+++ b/tests/aws-cpp-sdk-s3-integration-tests/BucketAndObjectOperationTest.cpp
@@ -49,7 +49,7 @@
 #include <fstream>
 #include <thread>
 
-#ifdef _WIN32
+#ifdef _MSC_VER
 #pragma warning(disable: 4127)
 #ifdef GetObject
 #undef GetObject
diff --git a/tests/testing-resources/include/aws/testing/AwsProtocolTestHelpers.h b/tests/testing-resources/include/aws/testing/AwsProtocolTestHelpers.h
index 18189aa6cdd..16e44472b09 100644
--- a/tests/testing-resources/include/aws/testing/AwsProtocolTestHelpers.h
+++ b/tests/testing-resources/include/aws/testing/AwsProtocolTestHelpers.h
@@ -6,7 +6,7 @@
 #pragma once
 
 #include <aws/testing/Testing_EXPORTS.h>
-#include <aws/testing/AwsCppSdkGTestSuite.h>s
+#include <aws/testing/AwsCppSdkGTestSuite.h>
 #include <aws/testing/AwsTestHelpers.h>
 
 
diff --git a/tests/testing-resources/source/platform/windows/PlatformTesting.cpp b/tests/testing-resources/source/platform/windows/PlatformTesting.cpp
index f3c375a2c16..729c2e01708 100644
--- a/tests/testing-resources/source/platform/windows/PlatformTesting.cpp
+++ b/tests/testing-resources/source/platform/windows/PlatformTesting.cpp
@@ -5,7 +5,9 @@
 
 #include <aws/testing/platform/PlatformTesting.h>
 
+#ifdef _MSC_VER
 #pragma warning(disable: 4996)
+#endif
 #include <windows.h>
 #include <aws/core/utils/memory/stl/AWSStringStream.h>