diff --git a/.github/workflows/c-cpp.yml b/.github/workflows/c-cpp.yml
index 0128eef..3212a65 100644
--- a/.github/workflows/c-cpp.yml
+++ b/.github/workflows/c-cpp.yml
@@ -7,7 +7,7 @@ on:
     branches: [ master ]
 
 jobs:
-  build:
+  build-ubuntu:
 
     runs-on: ubuntu-latest
 
@@ -34,3 +34,79 @@ jobs:
 
     - name: run tests
       run: cd tests/build && ./p2pool_tests
+
+  build-windows-msys2:
+
+    runs-on: windows-latest
+
+    defaults:
+      run:
+        shell: msys2 {0}
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v2
+      with:
+        submodules: recursive
+
+    - name: Setup MSYS2
+      uses: eine/setup-msys2@v2
+      with:
+        update: true
+        install: mingw-w64-x86_64-toolchain make mingw-w64-x86_64-cmake mingw-w64-x86_64-zeromq mingw-w64-x86_64-libsodium mingw-w64-x86_64-libuv
+
+    - name: Build p2pool
+      run: |
+        mkdir build
+        cd build
+        cmake .. -G "Unix Makefiles"
+        make
+
+    - name: Build tests
+      run: |
+        cd tests
+        mkdir build
+        cd build
+        cmake .. -G "Unix Makefiles"
+        make
+
+    - name: Run tests
+      run: |
+        cd tests/build
+        ./p2pool_tests.exe
+
+  build-windows-msbuild:
+
+    runs-on: windows-latest
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v2
+      with:
+        submodules: recursive
+
+    - name: Setup cmake
+      uses: lukka/get-cmake@latest
+
+    - name: Add msbuild to PATH
+      uses: microsoft/setup-msbuild@v1.0.3
+
+    - name: Build p2pool
+      run: |
+        mkdir build
+        cd build
+        cmake .. -G "Visual Studio 16 2019"
+        msbuild /m /p:Configuration=Release p2pool.vcxproj
+
+    - name: Build tests
+      run: |
+        cd tests
+        mkdir build
+        cd build
+        cmake .. -G "Visual Studio 16 2019"
+        msbuild /m /p:Configuration=Release p2pool_tests.vcxproj
+
+    - name: Run tests
+      run: |
+        cd tests/build/Release
+        ./p2pool_tests.exe
diff --git a/external/src/cryptonote/crypto-ops-data.c b/external/src/cryptonote/crypto-ops-data.c
index d16fd94..45bc23e 100644
--- a/external/src/cryptonote/crypto-ops-data.c
+++ b/external/src/cryptonote/crypto-ops-data.c
@@ -28,6 +28,10 @@
 // 
 // Parts of this file are originally copyright (c) 2012-2013 The Cryptonote developers
 
+#ifdef _MSC_VER
+#pragma warning(disable: 4146 4242 4244 4668 4710 4711 5045)
+#endif
+
 #include <stdint.h>
 
 #include "crypto-ops.h"
diff --git a/external/src/cryptonote/crypto-ops.c b/external/src/cryptonote/crypto-ops.c
index ad0a793..7ad465b 100644
--- a/external/src/cryptonote/crypto-ops.c
+++ b/external/src/cryptonote/crypto-ops.c
@@ -28,15 +28,15 @@
 // 
 // Parts of this file are originally copyright (c) 2012-2013 The Cryptonote developers
 
+#ifdef _MSC_VER
+#pragma warning(disable: 4146 4242 4244 4668 4710 4711 5045)
+#endif
+
 #include <assert.h>
 #include <stdint.h>
 
 #include "crypto-ops.h"
 
-#ifdef _MSC_VER
-#pragma warning(disable: 4146 4242 4244 4711 5045)
-#endif
-
 /* Predeclarations */
 
 static void fe_mul(fe, const fe, const fe);
diff --git a/external/src/llhttp/api.c b/external/src/llhttp/api.c
index 891ab93..4d68b4c 100644
--- a/external/src/llhttp/api.c
+++ b/external/src/llhttp/api.c
@@ -1,13 +1,13 @@
-#include <stdlib.h>
-#include <stdio.h>
-#include <string.h>
-
 #ifdef _MSC_VER
-#pragma warning(disable : 4100 4710 4711 4820)
+#pragma warning(disable : 4100 4668 4710 4711 4820)
 #elif defined __GNUC__
 #pragma GCC diagnostic ignored "-Wunused-parameter"
 #endif
 
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
 #include "llhttp.h"
 
 #define CALLBACK_MAYBE(PARSER, NAME)                                          \
diff --git a/external/src/llhttp/http.c b/external/src/llhttp/http.c
index 09c0dc4..dd406af 100644
--- a/external/src/llhttp/http.c
+++ b/external/src/llhttp/http.c
@@ -1,5 +1,5 @@
 #ifdef _MSC_VER
-#pragma warning(disable : 4100 4711 4820)
+#pragma warning(disable : 4100 4668 4710 4711 4820)
 #elif defined __GNUC__
 #pragma GCC diagnostic ignored "-Wunused-parameter"
 #endif
diff --git a/external/src/llhttp/llhttp.c b/external/src/llhttp/llhttp.c
index fe10574..b025b02 100644
--- a/external/src/llhttp/llhttp.c
+++ b/external/src/llhttp/llhttp.c
@@ -1,5 +1,5 @@
 #ifdef _MSC_VER
-#pragma warning(disable : 4061 4065 4100 4152 4242 4244 4668 4702 4820 5045)
+#pragma warning(disable : 4061 4065 4100 4152 4242 4244 4668 4702 4710 4711 4820 5045)
 #elif defined __GNUC__
 #pragma GCC diagnostic ignored "-Wunused-parameter"
 #endif
diff --git a/src/p2pool_api.cpp b/src/p2pool_api.cpp
index 7b20848..e8a88b1 100644
--- a/src/p2pool_api.cpp
+++ b/src/p2pool_api.cpp
@@ -75,7 +75,11 @@ void p2pool_api::create_dir(const std::string& path)
 #ifdef _MSC_VER
 	int result = _mkdir(path.c_str());
 #else
-	int result = mkdir(path.c_str(), 0775);
+	int result = mkdir(path.c_str()
+#ifndef _WIN32
+		, 0775
+#endif
+	);
 #endif
 
 	if (result < 0) {
diff --git a/tests/src/keccak_tests.cpp b/tests/src/keccak_tests.cpp
index 4f22cca..36e4071 100644
--- a/tests/src/keccak_tests.cpp
+++ b/tests/src/keccak_tests.cpp
@@ -38,7 +38,7 @@ TEST(keccak, hashing)
 		memset(buf, 0, sizeof(buf));
 		s.m_pos = 0;
 
-		keccak_custom([data](int offset) { return data[offset]; }, size, output.h, HASH_SIZE);
+		keccak_custom([data](int offset) { return data[offset]; }, len, output.h, HASH_SIZE);
 		s << output;
 		ASSERT_EQ(memcmp(buf, expected_output, HASH_SIZE * 2), 0);
 	};