Index: socketmodule.c
===================================================================
--- socketmodule.c	(revision 46167)
+++ socketmodule.c	(working copy)
@@ -416,8 +416,9 @@
 #define IS_SELECTABLE(s) 1
 #else
 /* POSIX says selecting file descriptors beyond FD_SETSIZE
-   has undefined behaviour. */
-#define IS_SELECTABLE(s) ((s)->sock_fd < FD_SETSIZE)
+   has undefined behaviour, however, we only ever call it if s->sock_timeout is
+   positive. */
+#define IS_SELECTABLE(s) ((s)->sock_fd < FD_SETSIZE || s->sock_timeout <= 0.0)
 #endif
 
 static PyObject*