diff --git a/ompi/debuggers/ompi_totalview.c b/ompi/debuggers/ompi_totalview.c
index 52a20137ff..0d20669e10 100644
--- a/ompi/debuggers/ompi_totalview.c
+++ b/ompi/debuggers/ompi_totalview.c
@@ -54,7 +54,7 @@ void ompi_wait_for_totalview(void)
                                 &wait_for_totalview);
     if (wait_for_totalview) {
         while (MPIR_debug_gate == 0) {
-#if defined(WIN32)
+#if defined(__WINDOWS__)
             sleep(100);     /* milliseconds */
 #else
             usleep(100000); /* microseconds */
diff --git a/ompi/include/ompi_socket_errno.h b/ompi/include/ompi_socket_errno.h
index 2f6f59bd7b..f9cab8731f 100644
--- a/ompi/include/ompi_socket_errno.h
+++ b/ompi/include/ompi_socket_errno.h
@@ -29,7 +29,7 @@
 
 #include <errno.h>
 #include "ompi/include/constants.h"
-#ifdef _WIN32
+#ifdef __WINDOWS__
 #define ompi_socket_errno ompi_get_socket_errno()
 
 #define EWOULDBLOCK       WSAEWOULDBLOCK       
diff --git a/ompi/include/types.h b/ompi/include/types.h
index a8656ddd85..65bad29ba5 100644
--- a/ompi/include/types.h
+++ b/ompi/include/types.h
@@ -31,7 +31,7 @@
 #include <sys/select.h>
 #endif
 
-#ifndef _WIN32
+#ifndef __WINDOWS__
 /*
  *  Increase FD_SETSIZE
  */
@@ -93,7 +93,7 @@ typedef union {
  * handle differences in iovec
  */
 
-#if defined(__APPLE__) || defined(_WIN32)
+#if defined(__APPLE__) || defined(__WINDOWS__)
 typedef char* ompi_iov_base_ptr_t;
 #else
 typedef void* ompi_iov_base_ptr_t;
diff --git a/ompi/mca/io/base/io_base_open.c b/ompi/mca/io/base/io_base_open.c
index bebf2f1ae5..4f49d6b533 100644
--- a/ompi/mca/io/base/io_base_open.c
+++ b/ompi/mca/io/base/io_base_open.c
@@ -35,7 +35,7 @@
  * statements and the definition of an array of pointers to each
  * component's public mca_base_component_t struct.
  */
-#ifdef WIN32
+#ifdef __WINDOWS__
     const mca_base_component_t *mca_io_base_static_components[] = {NULL};
 #else 
 #include "ompi/mca/io/base/static-components.h"
diff --git a/ompi/mca/mpool/base/mpool_base_open.c b/ompi/mca/mpool/base/mpool_base_open.c
index f525b257f7..307e07fbe4 100644
--- a/ompi/mca/mpool/base/mpool_base_open.c
+++ b/ompi/mca/mpool/base/mpool_base_open.c
@@ -34,7 +34,7 @@
  * component's public mca_base_component_t struct.
  */
 
-#ifdef WIN32
+#ifdef __WINDOWS__
     const mca_base_component_t *mca_mpool_base_static_components[] = {NULL};
 #else 
 #include "ompi/mca/mpool/base/static-components.h"
diff --git a/ompi/mca/rcache/base/rcache_base_open.c b/ompi/mca/rcache/base/rcache_base_open.c
index 422e031e3a..4b6e3cfefc 100644
--- a/ompi/mca/rcache/base/rcache_base_open.c
+++ b/ompi/mca/rcache/base/rcache_base_open.c
@@ -32,7 +32,7 @@
  * component's public mca_base_component_t struct.
  */
 
-#ifdef WIN32
+#ifdef __WINDOWS__
     const mca_base_component_t *mca_rcache_base_static_components[] = {NULL};
 #else 
 #include "ompi/mca/rcache/base/static-components.h"
diff --git a/ompi/runtime/ompi_mpi_io.c b/ompi/runtime/ompi_mpi_io.c
index ec01de8605..616383b5e1 100644
--- a/ompi/runtime/ompi_mpi_io.c
+++ b/ompi/runtime/ompi_mpi_io.c
@@ -26,7 +26,7 @@ int ompi_mpi_init_io(void)
     int fds[2];
     int rc;
 
-#ifndef WIN32
+#ifndef __WINDOWS__
     /* We need to add a NULL component for iof. Until then, this will have to do */
     /* setup stdin */
     rc = pipe(fds);