diff --git a/binding.gyp b/binding.gyp
index fb7c1c1..f1bba59 100644
--- a/binding.gyp
+++ b/binding.gyp
@@ -6,6 +6,7 @@
         "src/Main.cpp",
         "src/DiffWorkerCallback.cpp",
         "src/PatchWorkerCallback.cpp",
+        "src/Util.cpp",
         "src/c/bsdiff/bsdiff.c",
         "src/c/bspatch/bspatch.c",
         "src/c/bzip2/bzlib.c",
diff --git a/src/Main.cpp b/src/Main.cpp
index d172a8c..0eb520c 100644
--- a/src/Main.cpp
+++ b/src/Main.cpp
@@ -22,21 +22,21 @@ namespace bsdpNode {
     Nan::Callback *callback = new Nan::Callback(args[3].As<v8::Function>());
 
     Nan::Utf8String param0(args[0]);
-#ifdef WIN32
+#ifdef _WIN32
     std::string oldfile = Utf8ToAnsi(*param0);
 #else
     std::string oldfile = std::string(*param0);
 #endif
 
     Nan::Utf8String param1(args[1]);
-#ifdef WIN32
+#ifdef _WIN32
     std::string newfile = Utf8ToAnsi(*param1);
 #else
     std::string newfile = std::string(*param1);
 #endif
 
     Nan::Utf8String param2(args[2]);
-#ifdef WIN32
+#ifdef _WIN32
     std::string patchfile = Utf8ToAnsi(*param2);
 #else
 std::string patchfile = std::string(*param2);
@@ -65,7 +65,7 @@ std::string patchfile = std::string(*param2);
     char error[1024];
     memset(error, 0, sizeof error);
 
-#ifdef WIN32
+#ifdef _WIN32
     int ret = bsdiff(error, Utf8ToAnsi(*oldfile).c_str(), Utf8ToAnsi(*newfile).c_str(), Utf8ToAnsi(*patchfile).c_str(), nullptr, nullptr);
 #else
     int ret = bsdiff(error, *oldfile, *newfile, *patchfile, nullptr, nullptr);
@@ -86,21 +86,21 @@ std::string patchfile = std::string(*param2);
     Nan::Callback *callback = new Nan::Callback(args[3].As<v8::Function>());
 
     Nan::Utf8String param0(args[0]);
-#ifdef WIN32
+#ifdef _WIN32
     std::string oldfile = Utf8ToAnsi(*param0);
 #else
     std::string oldfile = std::string(*param0);
 #endif
 
     Nan::Utf8String param1(args[1]);
-#ifdef WIN32
+#ifdef _WIN32
     std::string newfile = Utf8ToAnsi(*param1);
 #else
     std::string newfile = std::string(*param1);
 #endif
 
     Nan::Utf8String param2(args[2]);
-#ifdef WIN32
+#ifdef _WIN32
     std::string patchfile = Utf8ToAnsi(*param2);
 #else
 std::string patchfile = std::string(*param2);
@@ -128,7 +128,7 @@ std::string patchfile = std::string(*param2);
     char error[1024];
     memset(error, 0, sizeof error);
 
-#ifdef WIN32
+#ifdef _WIN32
     int ret = bspatch(error, Utf8ToAnsi(*oldfile).c_str(), Utf8ToAnsi(*newfile).c_str(), Utf8ToAnsi(*patchfile).c_str(), nullptr, nullptr);
 #else
     int ret = bspatch(error, *oldfile, *newfile, *patchfile, nullptr, nullptr);
diff --git a/src/Util.cpp b/src/Util.cpp
index f981055..78cfb49 100644
--- a/src/Util.cpp
+++ b/src/Util.cpp
@@ -1,9 +1,11 @@
 #include "Util.hpp"
 
+#ifdef _WIN32
 #include <Windows.h>
+#endif
 
 namespace bsdpNode {
-#ifdef WIN32
+#ifdef _WIN32
   std::string Utf8ToAnsi(const std::string& utf8str)
   {
     int wcsLen = ::MultiByteToWideChar(CP_UTF8, NULL, utf8str.c_str(), strlen(utf8str.c_str()), NULL, 0);
diff --git a/src/Util.hpp b/src/Util.hpp
index ebdee65..074c354 100644
--- a/src/Util.hpp
+++ b/src/Util.hpp
@@ -1,12 +1,12 @@
-#ifndef Uitl_H
-#define Uitl_H
+#ifndef Util_H
+#define Util_H
 
 #include <string>
 
 namespace bsdpNode {
-#ifdef WIN32
+#ifdef _WIN32
     std::string Utf8ToAnsi(const std::string& utf8str);
 #endif
 }
 
-#endif  // Uitl_H
\ No newline at end of file
+#endif  // Util_H
\ No newline at end of file