diff --git a/example/direct_tcpip.c b/example/direct_tcpip.c
index 92bb7ca3..ac5e1317 100644
--- a/example/direct_tcpip.c
+++ b/example/direct_tcpip.c
@@ -6,7 +6,7 @@
 #include "libssh2_setup.h"
 #include <libssh2.h>
 
-#ifdef WIN32
+#ifdef _WIN32
 #include <ws2tcpip.h>  /* for socklen_t */
 #define recv(s, b, l, f)  recv((s), (b), (int)(l), (f))
 #define send(s, b, l, f)  send((s), (b), (int)(l), (f))
@@ -72,7 +72,7 @@ int main(int argc, char *argv[])
     libssh2_socket_t listensock = LIBSSH2_INVALID_SOCKET;
     libssh2_socket_t forwardsock = LIBSSH2_INVALID_SOCKET;
 
-#ifdef WIN32
+#ifdef _WIN32
     char sockopt;
     WSADATA wsadata;
 
@@ -311,7 +311,7 @@ shutdown:
 
     if(forwardsock != LIBSSH2_INVALID_SOCKET) {
         shutdown(forwardsock, 2);
-#ifdef WIN32
+#ifdef _WIN32
         closesocket(forwardsock);
 #else
         close(forwardsock);
@@ -320,7 +320,7 @@ shutdown:
 
     if(listensock != LIBSSH2_INVALID_SOCKET) {
         shutdown(listensock, 2);
-#ifdef WIN32
+#ifdef _WIN32
         closesocket(listensock);
 #else
         close(listensock);
@@ -337,7 +337,7 @@ shutdown:
 
     if(sock != LIBSSH2_INVALID_SOCKET) {
         shutdown(sock, 2);
-#ifdef WIN32
+#ifdef _WIN32
         closesocket(sock);
 #else
         close(sock);
diff --git a/example/scp.c b/example/scp.c
index c399eda8..62cac040 100644
--- a/example/scp.c
+++ b/example/scp.c
@@ -8,7 +8,7 @@
 #include "libssh2_setup.h"
 #include <libssh2.h>
 
-#ifdef WIN32
+#ifdef _WIN32
 #define write(f, b, c)  write((f), (b), (unsigned int)(c))
 #endif
 
@@ -46,7 +46,7 @@ int main(int argc, char *argv[])
     libssh2_struct_stat fileinfo;
     libssh2_struct_stat_size got = 0;
 
-#ifdef WIN32
+#ifdef _WIN32
     WSADATA wsadata;
 
     rc = WSAStartup(MAKEWORD(2, 0), &wsadata);
@@ -182,7 +182,7 @@ shutdown:
 
     if(sock != LIBSSH2_INVALID_SOCKET) {
         shutdown(sock, 2);
-#ifdef WIN32
+#ifdef _WIN32
         closesocket(sock);
 #else
         close(sock);
diff --git a/example/scp_nonblock.c b/example/scp_nonblock.c
index 4a38e034..da256deb 100644
--- a/example/scp_nonblock.c
+++ b/example/scp_nonblock.c
@@ -13,7 +13,7 @@
 #include "libssh2_setup.h"
 #include <libssh2.h>
 
-#ifdef WIN32
+#ifdef _WIN32
 #define write(f, b, c)  write((f), (b), (unsigned int)(c))
 #endif
 
@@ -100,7 +100,7 @@ int main(int argc, char *argv[])
     libssh2_struct_stat_size got = 0;
     libssh2_struct_stat_size total = 0;
 
-#ifdef WIN32
+#ifdef _WIN32
     WSADATA wsadata;
 
     rc = WSAStartup(MAKEWORD(2, 0), &wsadata);
@@ -285,7 +285,7 @@ shutdown:
 
     if(sock != LIBSSH2_INVALID_SOCKET) {
         shutdown(sock, 2);
-#ifdef WIN32
+#ifdef _WIN32
         closesocket(sock);
 #else
         close(sock);
diff --git a/example/scp_write.c b/example/scp_write.c
index 3305e2ef..b48edd2b 100644
--- a/example/scp_write.c
+++ b/example/scp_write.c
@@ -46,7 +46,7 @@ int main(int argc, char *argv[])
     char *ptr;
     struct stat fileinfo;
 
-#ifdef WIN32
+#ifdef _WIN32
     WSADATA wsadata;
 
     rc = WSAStartup(MAKEWORD(2, 0), &wsadata);
@@ -211,7 +211,7 @@ shutdown:
 
     if(sock != LIBSSH2_INVALID_SOCKET) {
         shutdown(sock, 2);
-#ifdef WIN32
+#ifdef _WIN32
         closesocket(sock);
 #else
         close(sock);
diff --git a/example/scp_write_nonblock.c b/example/scp_write_nonblock.c
index 60360303..daa19ad8 100644
--- a/example/scp_write_nonblock.c
+++ b/example/scp_write_nonblock.c
@@ -81,7 +81,7 @@ int main(int argc, char *argv[])
     int duration;
     size_t prev;
 
-#ifdef WIN32
+#ifdef _WIN32
     WSADATA wsadata;
 
     rc = WSAStartup(MAKEWORD(2, 0), &wsadata);
@@ -271,7 +271,7 @@ shutdown:
 
     if(sock != LIBSSH2_INVALID_SOCKET) {
         shutdown(sock, 2);
-#ifdef WIN32
+#ifdef _WIN32
         closesocket(sock);
 #else
         close(sock);
diff --git a/example/sftp.c b/example/sftp.c
index f65e1858..e941e0c3 100644
--- a/example/sftp.c
+++ b/example/sftp.c
@@ -14,7 +14,7 @@
 #include <libssh2.h>
 #include <libssh2_sftp.h>
 
-#ifdef WIN32
+#ifdef _WIN32
 #define write(f, b, c)  write((f), (b), (unsigned int)(c))
 #endif
 
@@ -101,7 +101,7 @@ int main(int argc, char *argv[])
     LIBSSH2_SFTP *sftp_session;
     LIBSSH2_SFTP_HANDLE *sftp_handle;
 
-#ifdef WIN32
+#ifdef _WIN32
     WSADATA wsadata;
 
     rc = WSAStartup(MAKEWORD(2, 0), &wsadata);
@@ -294,7 +294,7 @@ shutdown:
 
     if(sock != LIBSSH2_INVALID_SOCKET) {
         shutdown(sock, 2);
-#ifdef WIN32
+#ifdef _WIN32
         closesocket(sock);
 #else
         close(sock);
diff --git a/example/sftp_RW_nonblock.c b/example/sftp_RW_nonblock.c
index b657dacb..2d37f375 100644
--- a/example/sftp_RW_nonblock.c
+++ b/example/sftp_RW_nonblock.c
@@ -14,7 +14,7 @@
 #include <libssh2.h>
 #include <libssh2_sftp.h>
 
-#ifdef WIN32
+#ifdef _WIN32
 #define write(f, b, c)  write((f), (b), (unsigned int)(c))
 #endif
 
@@ -85,7 +85,7 @@ int main(int argc, char *argv[])
     fd_set fd;
     fd_set fd2;
 
-#ifdef WIN32
+#ifdef _WIN32
     WSADATA wsadata;
 
     rc = WSAStartup(MAKEWORD(2, 0), &wsadata);
@@ -342,7 +342,7 @@ shutdown:
 
     if(sock != LIBSSH2_INVALID_SOCKET) {
         shutdown(sock, 2);
-#ifdef WIN32
+#ifdef _WIN32
         closesocket(sock);
 #else
         close(sock);
diff --git a/example/sftp_append.c b/example/sftp_append.c
index bb9c819f..b82ebc72 100644
--- a/example/sftp_append.c
+++ b/example/sftp_append.c
@@ -54,7 +54,7 @@ int main(int argc, char *argv[])
     ssize_t nwritten;
     char *ptr;
 
-#ifdef WIN32
+#ifdef _WIN32
     WSADATA wsadata;
 
     rc = WSAStartup(MAKEWORD(2, 0), &wsadata);
@@ -231,7 +231,7 @@ shutdown:
 
     if(sock != LIBSSH2_INVALID_SOCKET) {
         shutdown(sock, 2);
-#ifdef WIN32
+#ifdef _WIN32
         closesocket(sock);
 #else
         close(sock);
diff --git a/example/sftp_mkdir.c b/example/sftp_mkdir.c
index f14c02bd..50bb2c4c 100644
--- a/example/sftp_mkdir.c
+++ b/example/sftp_mkdir.c
@@ -46,7 +46,7 @@ int main(int argc, char *argv[])
     LIBSSH2_SESSION *session = NULL;
     LIBSSH2_SFTP *sftp_session;
 
-#ifdef WIN32
+#ifdef _WIN32
     WSADATA wsadata;
 
     rc = WSAStartup(MAKEWORD(2, 0), &wsadata);
@@ -172,7 +172,7 @@ shutdown:
 
     if(sock != LIBSSH2_INVALID_SOCKET) {
         shutdown(sock, 2);
-#ifdef WIN32
+#ifdef _WIN32
         closesocket(sock);
 #else
         close(sock);
diff --git a/example/sftp_mkdir_nonblock.c b/example/sftp_mkdir_nonblock.c
index 0455b7e5..a10007dc 100644
--- a/example/sftp_mkdir_nonblock.c
+++ b/example/sftp_mkdir_nonblock.c
@@ -46,7 +46,7 @@ int main(int argc, char *argv[])
     LIBSSH2_SESSION *session = NULL;
     LIBSSH2_SFTP *sftp_session;
 
-#ifdef WIN32
+#ifdef _WIN32
     WSADATA wsadata;
 
     rc = WSAStartup(MAKEWORD(2, 0), &wsadata);
@@ -171,7 +171,7 @@ shutdown:
 
     if(sock != LIBSSH2_INVALID_SOCKET) {
         shutdown(sock, 2);
-#ifdef WIN32
+#ifdef _WIN32
         closesocket(sock);
 #else
         close(sock);
diff --git a/example/sftp_nonblock.c b/example/sftp_nonblock.c
index a18f3006..33db0879 100644
--- a/example/sftp_nonblock.c
+++ b/example/sftp_nonblock.c
@@ -14,7 +14,7 @@
 #include <libssh2.h>
 #include <libssh2_sftp.h>
 
-#ifdef WIN32
+#ifdef _WIN32
 #define write(f, b, c)  write((f), (b), (unsigned int)(c))
 #endif
 
@@ -100,7 +100,7 @@ int main(int argc, char *argv[])
     libssh2_struct_stat_size total = 0;
     int spin = 0;
 
-#ifdef WIN32
+#ifdef _WIN32
     WSADATA wsadata;
 
     rc = WSAStartup(MAKEWORD(2, 0), &wsadata);
@@ -288,7 +288,7 @@ shutdown:
 
     if(sock != LIBSSH2_INVALID_SOCKET) {
         shutdown(sock, 2);
-#ifdef WIN32
+#ifdef _WIN32
         closesocket(sock);
 #else
         close(sock);
diff --git a/example/sftp_write.c b/example/sftp_write.c
index ea901420..15effe21 100644
--- a/example/sftp_write.c
+++ b/example/sftp_write.c
@@ -53,7 +53,7 @@ int main(int argc, char *argv[])
     ssize_t nwritten;
     char *ptr;
 
-#ifdef WIN32
+#ifdef _WIN32
     WSADATA wsadata;
 
     rc = WSAStartup(MAKEWORD(2, 0), &wsadata);
@@ -215,7 +215,7 @@ shutdown:
 
     if(sock != LIBSSH2_INVALID_SOCKET) {
         shutdown(sock, 2);
-#ifdef WIN32
+#ifdef _WIN32
         closesocket(sock);
 #else
         close(sock);
diff --git a/example/sftp_write_nonblock.c b/example/sftp_write_nonblock.c
index fd3c58f6..ad279031 100644
--- a/example/sftp_write_nonblock.c
+++ b/example/sftp_write_nonblock.c
@@ -87,7 +87,7 @@ int main(int argc, char *argv[])
     libssh2_struct_stat_size total = 0;
     int duration;
 
-#ifdef WIN32
+#ifdef _WIN32
     WSADATA wsadata;
 
     rc = WSAStartup(MAKEWORD(2, 0), &wsadata);
@@ -273,7 +273,7 @@ shutdown:
 
     if(sock != LIBSSH2_INVALID_SOCKET) {
         shutdown(sock, 2);
-#ifdef WIN32
+#ifdef _WIN32
         closesocket(sock);
 #else
         close(sock);
diff --git a/example/sftp_write_sliding.c b/example/sftp_write_sliding.c
index 4df497c2..b11b5659 100644
--- a/example/sftp_write_sliding.c
+++ b/example/sftp_write_sliding.c
@@ -88,7 +88,7 @@ int main(int argc, char *argv[])
     libssh2_struct_stat_size total = 0;
     int duration;
 
-#ifdef WIN32
+#ifdef _WIN32
     WSADATA wsadata;
 
     rc = WSAStartup(MAKEWORD(2, 0), &wsadata);
@@ -284,7 +284,7 @@ shutdown:
 
     if(sock != LIBSSH2_INVALID_SOCKET) {
         shutdown(sock, 2);
-#ifdef WIN32
+#ifdef _WIN32
         closesocket(sock);
 #else
         close(sock);
diff --git a/example/sftpdir.c b/example/sftpdir.c
index f8176e9b..477f1d86 100644
--- a/example/sftpdir.c
+++ b/example/sftpdir.c
@@ -74,7 +74,7 @@ int main(int argc, char *argv[])
     LIBSSH2_SFTP *sftp_session;
     LIBSSH2_SFTP_HANDLE *sftp_handle;
 
-#ifdef WIN32
+#ifdef _WIN32
     WSADATA wsadata;
 
     rc = WSAStartup(MAKEWORD(2, 0), &wsadata);
@@ -295,7 +295,7 @@ shutdown:
 
     if(sock != LIBSSH2_INVALID_SOCKET) {
         shutdown(sock, 2);
-#ifdef WIN32
+#ifdef _WIN32
         closesocket(sock);
 #else
         close(sock);
diff --git a/example/sftpdir_nonblock.c b/example/sftpdir_nonblock.c
index e21026c3..360982f3 100644
--- a/example/sftpdir_nonblock.c
+++ b/example/sftpdir_nonblock.c
@@ -53,7 +53,7 @@ int main(int argc, char *argv[])
     LIBSSH2_SFTP *sftp_session;
     LIBSSH2_SFTP_HANDLE *sftp_handle;
 
-#ifdef WIN32
+#ifdef _WIN32
     WSADATA wsadata;
 
     rc = WSAStartup(MAKEWORD(2, 0), &wsadata);
@@ -235,7 +235,7 @@ shutdown:
 
     if(sock != LIBSSH2_INVALID_SOCKET) {
         shutdown(sock, 2);
-#ifdef WIN32
+#ifdef _WIN32
         closesocket(sock);
 #else
         close(sock);
diff --git a/example/ssh2.c b/example/ssh2.c
index 8dd71b36..08e2398f 100644
--- a/example/ssh2.c
+++ b/example/ssh2.c
@@ -71,7 +71,7 @@ int main(int argc, char *argv[])
     LIBSSH2_SESSION *session = NULL;
     LIBSSH2_CHANNEL *channel;
 
-#ifdef WIN32
+#ifdef _WIN32
     WSADATA wsadata;
 
     rc = WSAStartup(MAKEWORD(2, 0), &wsadata);
@@ -341,7 +341,7 @@ shutdown:
 
     if(sock != LIBSSH2_INVALID_SOCKET) {
         shutdown(sock, 2);
-#ifdef WIN32
+#ifdef _WIN32
         closesocket(sock);
 #else
         close(sock);
diff --git a/example/ssh2_agent.c b/example/ssh2_agent.c
index 47d02072..3ab1d9ba 100644
--- a/example/ssh2_agent.c
+++ b/example/ssh2_agent.c
@@ -44,7 +44,7 @@ int main(int argc, char *argv[])
     LIBSSH2_AGENT *agent = NULL;
     struct libssh2_agent_publickey *identity, *prev_identity = NULL;
 
-#ifdef WIN32
+#ifdef _WIN32
     WSADATA wsadata;
 
     rc = WSAStartup(MAKEWORD(2, 0), &wsadata);
@@ -238,7 +238,7 @@ shutdown:
 
     if(sock != LIBSSH2_INVALID_SOCKET) {
         shutdown(sock, 2);
-#ifdef WIN32
+#ifdef _WIN32
         closesocket(sock);
 #else
         close(sock);
diff --git a/example/ssh2_agent_forwarding.c b/example/ssh2_agent_forwarding.c
index 6f1fd003..eef294c4 100644
--- a/example/ssh2_agent_forwarding.c
+++ b/example/ssh2_agent_forwarding.c
@@ -80,7 +80,7 @@ int main(int argc, char *argv[])
     char *exitsignal = (char *)"none";
     ssize_t bytecount = 0;
 
-#ifdef WIN32
+#ifdef _WIN32
     WSADATA wsadata;
 
     rc = WSAStartup(MAKEWORD(2, 0), &wsadata);
@@ -285,7 +285,7 @@ shutdown:
 
     if(sock != LIBSSH2_INVALID_SOCKET) {
         shutdown(sock, 2);
-#ifdef WIN32
+#ifdef _WIN32
         closesocket(sock);
 #else
         close(sock);
diff --git a/example/ssh2_echo.c b/example/ssh2_echo.c
index 884040b0..f5cecf3a 100644
--- a/example/ssh2_echo.c
+++ b/example/ssh2_echo.c
@@ -80,7 +80,7 @@ int main(int argc, char *argv[])
     LIBSSH2_KNOWNHOSTS *nh;
     int type;
 
-#ifdef WIN32
+#ifdef _WIN32
     WSADATA wsadata;
 
     rc = WSAStartup(MAKEWORD(2, 0), &wsadata);
@@ -356,7 +356,7 @@ shutdown:
 
     if(sock != LIBSSH2_INVALID_SOCKET) {
         shutdown(sock, 2);
-#ifdef WIN32
+#ifdef _WIN32
         closesocket(sock);
 #else
         close(sock);
diff --git a/example/ssh2_exec.c b/example/ssh2_exec.c
index f1398c1d..44de404a 100644
--- a/example/ssh2_exec.c
+++ b/example/ssh2_exec.c
@@ -83,7 +83,7 @@ int main(int argc, char *argv[])
     LIBSSH2_KNOWNHOSTS *nh;
     int type;
 
-#ifdef WIN32
+#ifdef _WIN32
     WSADATA wsadata;
 
     rc = WSAStartup(MAKEWORD(2, 0), &wsadata);
@@ -294,7 +294,7 @@ shutdown:
 
     if(sock != LIBSSH2_INVALID_SOCKET) {
         shutdown(sock, 2);
-#ifdef WIN32
+#ifdef _WIN32
         closesocket(sock);
 #else
         close(sock);
diff --git a/example/subsystem_netconf.c b/example/subsystem_netconf.c
index 31a71ecc..a9d3d385 100644
--- a/example/subsystem_netconf.c
+++ b/example/subsystem_netconf.c
@@ -112,7 +112,7 @@ int main(int argc, char *argv[])
     ssize_t len;
     libssh2_socket_t sock;
 
-#ifdef WIN32
+#ifdef _WIN32
     WSADATA wsadata;
 
     rc = WSAStartup(MAKEWORD(2, 0), &wsadata);
@@ -291,7 +291,7 @@ shutdown:
 
     if(sock != LIBSSH2_INVALID_SOCKET) {
         shutdown(sock, 2);
-#ifdef WIN32
+#ifdef _WIN32
         closesocket(sock);
 #else
         close(sock);
diff --git a/example/tcpip-forward.c b/example/tcpip-forward.c
index c105beac..8dfb016a 100644
--- a/example/tcpip-forward.c
+++ b/example/tcpip-forward.c
@@ -6,7 +6,7 @@
 #include "libssh2_setup.h"
 #include <libssh2.h>
 
-#ifdef WIN32
+#ifdef _WIN32
 #include <ws2tcpip.h>  /* for socklen_t */
 #define recv(s, b, l, f)  recv((s), (b), (int)(l), (f))
 #define send(s, b, l, f)  send((s), (b), (int)(l), (f))
@@ -73,7 +73,7 @@ int main(int argc, char *argv[])
     libssh2_socket_t sock;
     libssh2_socket_t forwardsock = LIBSSH2_INVALID_SOCKET;
 
-#ifdef WIN32
+#ifdef _WIN32
     WSADATA wsadata;
 
     rc = WSAStartup(MAKEWORD(2, 0), &wsadata);
@@ -306,7 +306,7 @@ shutdown:
 
     if(forwardsock != LIBSSH2_INVALID_SOCKET) {
         shutdown(forwardsock, 2);
-#ifdef WIN32
+#ifdef _WIN32
         closesocket(forwardsock);
 #else
         close(forwardsock);
@@ -326,7 +326,7 @@ shutdown:
 
     if(sock != LIBSSH2_INVALID_SOCKET) {
         shutdown(sock, 2);
-#ifdef WIN32
+#ifdef _WIN32
         closesocket(sock);
 #else
         close(sock);
diff --git a/src/agent.c b/src/agent.c
index d99a3195..a11645ee 100644
--- a/src/agent.c
+++ b/src/agent.c
@@ -53,7 +53,7 @@
 #undef PF_UNIX
 #endif
 
-#if defined(WIN32) && !defined(LIBSSH2_WINDOWS_UWP)
+#if defined(_WIN32) && !defined(LIBSSH2_WINDOWS_UWP)
 #define HAVE_WIN32_AGENTS
 #endif
 
diff --git a/src/libssh2_priv.h b/src/libssh2_priv.h
index 66cce068..5c3477ad 100644
--- a/src/libssh2_priv.h
+++ b/src/libssh2_priv.h
@@ -86,7 +86,7 @@
 #include "libssh2_sftp.h"
 #include "misc.h"
 
-#ifdef WIN32
+#ifdef _WIN32
 /* Detect Windows App environment which has a restricted access
    to the Win32 APIs. */
 # if (defined(_WIN32_WINNT) && (_WIN32_WINNT >= 0x0602)) || \
@@ -134,7 +134,7 @@ int _libssh2_gettimeofday(struct timeval *tp, void *tzp);
 #endif
 
 /* 3DS doesn't seem to have iovec */
-#if defined(WIN32) || defined(_3DS)
+#if defined(_WIN32) || defined(_3DS)
 
 struct iovec {
     size_t iov_len;
@@ -1204,12 +1204,12 @@ size_t plain_method(char *method, size_t method_len);
 /* In Windows the default file mode is text but an application can override it.
    Therefore we specify it explicitly. https://github.com/curl/curl/pull/258
  */
-#if defined(WIN32) || defined(MSDOS)
+#if defined(_WIN32) || defined(MSDOS)
 #define FOPEN_READTEXT "rt"
 #define FOPEN_WRITETEXT "wt"
 #define FOPEN_APPENDTEXT "at"
 #elif defined(__CYGWIN__)
-/* Cygwin has specific behavior we need to address when WIN32 is not defined.
+/* Cygwin has specific behavior we need to address when _WIN32 is not defined.
      https://cygwin.com/cygwin-ug-net/using-textbinary.html
    For write we want our output to have line endings of LF and be compatible
    with other Cygwin utilities. For read we want to handle input that may have
diff --git a/src/libssh2_setup.h b/src/libssh2_setup.h
index 8e56a060..7e084f99 100644
--- a/src/libssh2_setup.h
+++ b/src/libssh2_setup.h
@@ -9,10 +9,6 @@
 /* Header for platform/compiler-specific initialization.
    Used by 'src', 'example', 'tests' */
 
-#if defined(_WIN32) && !defined(WIN32)
-#define WIN32
-#endif
-
 /* Define mingw-w64 version macros, eg __MINGW{32,64}_{MINOR,MAJOR}_VERSION */
 #ifdef __MINGW32__
 #include <_mingw.h>
@@ -26,7 +22,7 @@
 
 /* Hand-crafted configuration for platforms which lack config tool.
    Keep this synced with root CMakeLists.txt */
-#elif defined(WIN32)
+#elif defined(_WIN32)
 
 #define HAVE_SELECT
 #define HAVE_SNPRINTF
@@ -54,7 +50,7 @@
 
 /* Below applies to both auto-detected and hand-crafted configs */
 
-#ifdef WIN32
+#ifdef _WIN32
 
 #ifndef WIN32_LEAN_AND_MEAN
 #define WIN32_LEAN_AND_MEAN
@@ -103,6 +99,6 @@
 # endif
 #endif
 
-#endif /* WIN32 */
+#endif /* _WIN32 */
 
 #endif /* LIBSSH2_SETUP_H */
diff --git a/src/misc.c b/src/misc.c
index b19df7a8..0897f828 100644
--- a/src/misc.c
+++ b/src/misc.c
@@ -48,7 +48,7 @@
 #include <errno.h>
 #include <assert.h>
 
-#ifdef WIN32
+#ifdef _WIN32
 /* Force parameter type. */
 #define recv(s, b, l, f)  recv((s), (b), (int)(l), (f))
 #define send(s, b, l, f)  send((s), (b), (int)(l), (f))
@@ -125,7 +125,7 @@ int _libssh2_error(LIBSSH2_SESSION* session, int errcode, const char *errmsg)
     return _libssh2_error_flags(session, errcode, errmsg, 0);
 }
 
-#ifdef WIN32
+#ifdef _WIN32
 static int wsa2errno(void)
 {
     switch(WSAGetLastError()) {
@@ -160,7 +160,7 @@ _libssh2_recv(libssh2_socket_t sock, void *buffer, size_t length,
     (void)abstract;
 
     rc = recv(sock, buffer, length, flags);
-#ifdef WIN32
+#ifdef _WIN32
     if(rc < 0)
         return -wsa2errno();
 #else
@@ -193,7 +193,7 @@ _libssh2_send(libssh2_socket_t sock, const void *buffer, size_t length,
     (void)abstract;
 
     rc = send(sock, buffer, length, flags);
-#ifdef WIN32
+#ifdef _WIN32
     if(rc < 0)
         return -wsa2errno();
 #else
@@ -708,7 +708,7 @@ int _libssh2_gettimeofday(struct timeval *tp, void *tzp)
 {
     (void)tzp;
     if(tp) {
-#ifdef WIN32
+#ifdef _WIN32
         /* Offset between 1601-01-01 and 1970-01-01 in 100 nanosec units */
         #define _WIN32_FT_OFFSET (116444736000000000)
 
diff --git a/src/misc.h b/src/misc.h
index 38d1f8e9..ccb5b9c5 100644
--- a/src/misc.h
+++ b/src/misc.h
@@ -44,7 +44,7 @@
                                               (void)(buf); \
                                               (void)(size); \
                                           } while(0)
-#elif defined(WIN32)
+#elif defined(_WIN32)
 #define _libssh2_explicit_zero(buf, size) SecureZeroMemory(buf, size)
 #elif defined(HAVE_EXPLICIT_BZERO)
 #define _libssh2_explicit_zero(buf, size) explicit_bzero(buf, size)
diff --git a/src/session.c b/src/session.c
index 4d9edc5c..41d7502d 100644
--- a/src/session.c
+++ b/src/session.c
@@ -41,7 +41,7 @@
 
 #include "libssh2_priv.h"
 
-#ifdef WIN32
+#ifdef _WIN32
 #include <ws2tcpip.h>  /* for socklen_t */
 #endif
 #ifdef HAVE_UNISTD_H
@@ -60,7 +60,7 @@
 #include "channel.h"
 #include "mac.h"
 
-#if defined(WIN32)
+#if defined(_WIN32)
 #define libssh2_usec_t long
 #elif defined(__APPLE__)
 #define libssh2_usec_t suseconds_t
@@ -313,7 +313,7 @@ session_nonblock(libssh2_socket_t sockfd,   /* operate on this */
     /* BeOS */
     long b = nonblock ? 1 : 0;
     return setsockopt(sockfd, SOL_SOCKET, SO_NONBLOCK, &b, sizeof(b));
-#elif defined(WIN32)
+#elif defined(_WIN32)
     unsigned long flags;
 
     flags = nonblock;
@@ -366,7 +366,7 @@ get_socket_nonblocking(libssh2_socket_t sockfd)
         return 1;
     }
     return 0;
-#elif defined(WIN32)
+#elif defined(_WIN32)
     unsigned int option_value;
     socklen_t option_len = sizeof(option_value);
 
diff --git a/tests/openssh_fixture.c b/tests/openssh_fixture.c
index bce9029d..e43a5d85 100644
--- a/tests/openssh_fixture.c
+++ b/tests/openssh_fixture.c
@@ -58,7 +58,7 @@
 #include <stdarg.h>
 #include <ctype.h>
 
-#if defined(WIN32) && defined(_WIN64)
+#if defined(_WIN32) && defined(_WIN64)
 #define LIBSSH2_SOCKET_MASK "%lld"
 #else
 #define LIBSSH2_SOCKET_MASK "%d"
@@ -67,7 +67,7 @@
 #ifdef LIBSSH2_WINDOWS_UWP
 #define popen(x, y) (NULL)
 #define pclose(x) (-1)
-#elif defined(WIN32)
+#elif defined(_WIN32)
 #define popen _popen
 #define pclose _pclose
 #endif
@@ -232,7 +232,7 @@ static const char *docker_machine_name(void)
 
 static int is_running_inside_a_container(void)
 {
-#ifdef WIN32
+#ifdef _WIN32
     return 0;
 #else
     const char *cgroup_filename = "/proc/self/cgroup";
@@ -260,7 +260,7 @@ static int is_running_inside_a_container(void)
 
 static void portable_sleep(unsigned int seconds)
 {
-#ifdef WIN32
+#ifdef _WIN32
     Sleep(seconds);
 #else
     sleep(seconds);
@@ -426,7 +426,7 @@ static void close_socket_to_container(libssh2_socket_t sock)
 {
     if(sock != LIBSSH2_INVALID_SOCKET) {
         shutdown(sock, 2 /* SHUT_RDWR */);
-#ifdef WIN32
+#ifdef _WIN32
         closesocket(sock);
 #else
         close(sock);
@@ -439,7 +439,7 @@ static char *running_container_id = NULL;
 int start_openssh_fixture(void)
 {
     int ret;
-#ifdef WIN32
+#ifdef _WIN32
     WSADATA wsadata;
 
     ret = WSAStartup(MAKEWORD(2, 0), &wsadata);
diff --git a/tests/session_fixture.c b/tests/session_fixture.c
index 6ee54989..4fedd882 100644
--- a/tests/session_fixture.c
+++ b/tests/session_fixture.c
@@ -252,7 +252,7 @@ void stop_session_fixture(void)
 #define NUMPATHS 32
 const char *srcdir_path(const char *file)
 {
-#ifdef WIN32
+#ifdef _WIN32
     static char filepath[NUMPATHS][_MAX_PATH];
 #else
     static char filepath[NUMPATHS][MAXPATHLEN];
@@ -458,7 +458,7 @@ int test_auth_pubkey(LIBSSH2_SESSION *session, int flags,
     /* Ignore our hard-wired Dockerfile user when not running under Docker */
     if(!openssh_fixture_have_docker() && strcmp(username, "libssh2") == 0) {
         username = getenv("USER");
-#ifdef WIN32
+#ifdef _WIN32
         if(!username)
             username = getenv("USERNAME");
 #endif
diff --git a/tests/test_read.c b/tests/test_read.c
index a248e3cc..af1f1796 100644
--- a/tests/test_read.c
+++ b/tests/test_read.c
@@ -38,7 +38,7 @@ int test(LIBSSH2_SESSION *session)
     /* Ignore our hard-wired Dockerfile user when not running under Docker */
     if(!openssh_fixture_have_docker()) {
         username = getenv("USER");
-#ifdef WIN32
+#ifdef _WIN32
         if(!username)
             username = getenv("USERNAME");
 #endif
diff --git a/tests/test_ssh2.c b/tests/test_ssh2.c
index 50a50e9a..90a7997d 100644
--- a/tests/test_ssh2.c
+++ b/tests/test_ssh2.c
@@ -33,7 +33,7 @@ static const char *password = "password";
 
 static void portable_sleep(unsigned int seconds)
 {
-#ifdef WIN32
+#ifdef _WIN32
     Sleep(seconds);
 #else
     sleep(seconds);
@@ -53,7 +53,7 @@ int main(int argc, char *argv[])
     LIBSSH2_CHANNEL *channel;
     int counter;
 
-#ifdef WIN32
+#ifdef _WIN32
     WSADATA wsadata;
 
     rc = WSAStartup(MAKEWORD(2, 0), &wsadata);
@@ -68,7 +68,7 @@ int main(int argc, char *argv[])
 
     if(getenv("USER"))
         username = getenv("USER");
-#ifdef WIN32
+#ifdef _WIN32
     else if(getenv("USERNAME"))
         username = getenv("USERNAME");
 #endif
@@ -254,7 +254,7 @@ shutdown:
 
     if(sock != LIBSSH2_INVALID_SOCKET) {
         shutdown(sock, 2 /* SHUT_RDWR */);
-#ifdef WIN32
+#ifdef _WIN32
         closesocket(sock);
 #else
         close(sock);