Index: include/ruby/win32.h
===================================================================
--- include/ruby/win32.h	(revision 35469)
+++ include/ruby/win32.h	(working copy)
@@ -581,13 +581,54 @@ extern char *rb_w32_strerror(int);
 #define O_NONBLOCK 1
 
 #undef FD_SET
-#define FD_SET(f, s)		rb_w32_fdset(f, s)
+#define FD_SET(f, s)		rb_w32_fdset_internal(f, s)
+static inline void
+rb_w32_fdset_internal(int fd, fd_set *set)
+{
+    unsigned int i;
+    SOCKET s = rb_w32_get_osfhandle(fd);
+
+    for (i = 0; i < set->fd_count; i++) {
+        if (set->fd_array[i] == s) {
+            return;
+        }
+    }
+    if (i == set->fd_count) {
+        if (set->fd_count < FD_SETSIZE) {
+            set->fd_array[i] = s;
+            set->fd_count++;
+        }
+    }
+}
 
 #undef FD_CLR
-#define FD_CLR(f, s)		rb_w32_fdclr(f, s)
+#define FD_CLR(f, s)		rb_w32_fdclr_internal(f, s)
+static inline void
+rb_w32_fdclr_internal(int fd, fd_set *set)
+{
+    unsigned int i;
+    SOCKET s = rb_w32_get_osfhandle(fd);
+
+    for (i = 0; i < set->fd_count; i++) {
+        if (set->fd_array[i] == s) {
+	    memmove(&set->fd_array[i], &set->fd_array[i+1],
+		    sizeof(set->fd_array[0]) * (--set->fd_count - i));
+            break;
+        }
+    }
+}
 
 #undef FD_ISSET
-#define FD_ISSET(f, s)		rb_w32_fdisset(f, s)
+#define FD_ISSET(f, s)		rb_w32_fdisset_internal(f, s)
+static inline int
+rb_w32_fdisset_internal(int fd, fd_set *set)
+{
+    int ret;
+    SOCKET s = rb_w32_get_osfhandle(fd);
+    if (s == (SOCKET)INVALID_HANDLE_VALUE)
+        return 0;
+    return __WSAFDIsSet(s, set);
+}
 
 #ifdef RUBY_EXPORT
 #undef inet_ntop
Index: win32/win32.c
===================================================================
--- win32/win32.c	(revision 35469)
+++ win32/win32.c	(working copy)
@@ -2452,59 +2452,30 @@ ioctl(int i, int u, ...)
     return -1;
 }
 
-#undef FD_SET
 
+/* for backward compatibility */
+/* License: Ruby's */
 void
 rb_w32_fdset(int fd, fd_set *set)
 {
-    unsigned int i;
-    SOCKET s = TO_SOCKET(fd);
-
-    for (i = 0; i < set->fd_count; i++) {
-        if (set->fd_array[i] == s) {
-            return;
-        }
-    }
-    if (i == set->fd_count) {
-        if (set->fd_count < FD_SETSIZE) {
-            set->fd_array[i] = s;
-            set->fd_count++;
-        }
-    }
+    rb_w32_fdset_internal(fd, set);
 }
 
-#undef FD_CLR
-
 /* License: Ruby's */
 void
 rb_w32_fdclr(int fd, fd_set *set)
 {
-    unsigned int i;
-    SOCKET s = TO_SOCKET(fd);
-
-    for (i = 0; i < set->fd_count; i++) {
-        if (set->fd_array[i] == s) {
-	    memmove(&set->fd_array[i], &set->fd_array[i+1],
-		    sizeof(set->fd_array[0]) * (--set->fd_count - i));
-            break;
-        }
-    }
+    rb_w32_fdclr_internal(fd, set);
 }
 
-#undef FD_ISSET
-
 /* License: Ruby's */
 int
 rb_w32_fdisset(int fd, fd_set *set)
 {
-    int ret;
-    SOCKET s = TO_SOCKET(fd);
-    if (s == (SOCKET)INVALID_HANDLE_VALUE)
-        return 0;
-    RUBY_CRITICAL(ret = __WSAFDIsSet(s, set));
-    return ret;
+    return rb_w32_fdisset_internal(fd, set);
 }
 
+
 /* License: Ruby's */
 void
 rb_w32_fd_copy(rb_fdset_t *dst, const fd_set *src, int max)