diff --git a/src/api.h b/src/api.h
index 24f1a02..db7b729 100644
--- a/src/api.h
+++ b/src/api.h
@@ -216,3 +216,3 @@ private:
    pthread_key_t m_TLSError;                         // thread local error record (last error)
-   #ifndef WIN32
+   #ifndef _WIN32
       static void TLSDestroy(void* e) {if (NULL != e) delete (CUDTException*)e;}
@@ -248,3 +248,3 @@ private:
    pthread_t m_GCThread;
-   #ifndef WIN32
+   #ifndef _WIN32
       static void* garbageCollect(void*);
diff --git a/src/common.h b/src/common.h
index 3782d61..205b090 100644
--- a/src/common.h
+++ b/src/common.h
@@ -44,3 +44,3 @@ written by
 
-#ifndef WIN32
+#ifndef _WIN32
    #include <sys/time.h>
@@ -55,3 +55,3 @@ written by
 
-#ifdef WIN32
+#ifdef _WIN32
    // Windows compability
diff --git a/src/packet.h b/src/packet.h
index 76cc951..216505a 100644
--- a/src/packet.h
+++ b/src/packet.h
@@ -46,3 +46,3 @@ written by
 
-#ifdef WIN32
+#ifdef _WIN32
    struct iovec
diff --git a/src/queue.h b/src/queue.h
index 9feff18..1062a0c 100644
--- a/src/queue.h
+++ b/src/queue.h
@@ -399,3 +399,3 @@ public:
 private:
-#ifndef WIN32
+#ifndef _WIN32
    static void* worker(void* param);
@@ -459,3 +459,3 @@ public:
 private:
-#ifndef WIN32
+#ifndef _WIN32
    static void* worker(void* param);
diff --git a/src/udt.h b/src/udt.h
index 6436363..8e00091 100644
--- a/src/udt.h
+++ b/src/udt.h
@@ -44,3 +44,3 @@ written by
 
-#ifndef WIN32
+#ifndef _WIN32
    #include <sys/types.h>
@@ -70,3 +70,3 @@ written by
 
-#ifdef WIN32
+#ifdef _WIN32
    #ifndef __MINGW__
@@ -97,3 +97,3 @@ written by
 
-#ifdef WIN32
+#ifdef _WIN32
    #ifndef __MINGW__
diff --git a/src/window.h b/src/window.h
index f118a26..565aeb6 100644
--- a/src/window.h
+++ b/src/window.h
@@ -44,3 +44,3 @@ written by
 
-#ifndef WIN32
+#ifndef _WIN32
    #include <sys/time.h>