diff --git a/ext/io/wait/extconf.rb b/ext/io/wait/extconf.rb
index b5d36c3fe3..d20ff4553f 100644
--- a/ext/io/wait/extconf.rb
+++ b/ext/io/wait/extconf.rb
@@ -2,6 +2,7 @@
 require 'mkmf'
 target = "io/wait"
 
+have_func("rb_io_wait")
 unless macro_defined?("DOSISH", "#include <ruby.h>")
   have_header(ioctl_h = "sys/ioctl.h") or ioctl_h = nil
   fionread = %w[sys/ioctl.h sys/filio.h sys/socket.h].find do |h|
diff --git a/ext/io/wait/wait.c b/ext/io/wait/wait.c
index 512e4f6a80..8f0d16e168 100644
--- a/ext/io/wait/wait.c
+++ b/ext/io/wait/wait.c
@@ -40,6 +40,37 @@
 #define FIONREAD_POSSIBLE_P(fd) ((void)(fd),Qtrue)
 #endif
 
+#ifndef HAVE_RB_IO_WAIT
+static VALUE io_ready_p _((VALUE io));
+static VALUE io_wait_readable _((int argc, VALUE *argv, VALUE io));
+static VALUE io_wait_writable _((int argc, VALUE *argv, VALUE io));
+void Init_wait _((void));
+
+static struct timeval *
+get_timeout(int argc, VALUE *argv, struct timeval *timerec)
+{
+    VALUE timeout = Qnil;
+    rb_check_arity(argc, 0, 1);
+    if (!argc || NIL_P(timeout = argv[0])) {
+	return NULL;
+    }
+    else {
+	*timerec = rb_time_interval(timeout);
+	return timerec;
+    }
+}
+
+static int
+wait_for_single_fd(rb_io_t *fptr, int events, struct timeval *tv)
+{
+    int i = rb_wait_for_single_fd(fptr->fd, events, tv);
+    if (i < 0)
+	rb_sys_fail(0);
+    rb_io_check_closed(fptr);
+    return (i & events);
+}
+#endif
+
 /*
  * call-seq:
  *   io.nread -> int
@@ -51,12 +82,13 @@
 static VALUE
 io_nread(VALUE io)
 {
-    rb_io_t *fptr = NULL;
+    rb_io_t *fptr;
+    int len;
     ioctl_arg n;
 
     GetOpenFile(io, fptr);
     rb_io_check_readable(fptr);
-    int len = rb_io_read_pending(fptr);
+    len = rb_io_read_pending(fptr);
     if (len > 0) return INT2FIX(len);
     if (!FIONREAD_POSSIBLE_P(fptr->fd)) return INT2FIX(0);
     if (ioctl(fptr->fd, FIONREAD, &n)) return INT2FIX(0);
@@ -64,6 +96,7 @@ io_nread(VALUE io)
     return INT2FIX(0);
 }
 
+#ifdef HAVE_RB_IO_WAIT
 static VALUE
 io_wait_event(VALUE io, int event, VALUE timeout)
 {
@@ -82,6 +115,7 @@ io_wait_event(VALUE io, int event, VALUE timeout)
 	return Qfalse;
     }
 }
+#endif
 
 /*
  * call-seq:
@@ -94,12 +128,22 @@ static VALUE
 io_ready_p(VALUE io)
 {
     rb_io_t *fptr;
+#ifndef HAVE_RB_IO_WAIT
+    struct timeval tv = {0, 0};
+#endif
 
     GetOpenFile(io, fptr);
     rb_io_check_readable(fptr);
     if (rb_io_read_pending(fptr)) return Qtrue;
 
-    return io_wait_event(io, RUBY_IO_READABLE, RB_INT2NUM(0));
+#ifndef HAVE_RB_IO_WAIT
+    if (wait_for_single_fd(fptr, RB_WAITFD_IN, &tv))
+	return Qtrue;
+#else
+    if (RTEST(io_wait_event(io, RUBY_IO_READABLE, RB_INT2NUM(0))))
+	return Qtrue;
+#endif
+    return Qfalse;
 }
 
 /*
@@ -115,17 +159,31 @@ io_ready_p(VALUE io)
 static VALUE
 io_wait_readable(int argc, VALUE *argv, VALUE io)
 {
-    rb_io_t *fptr = NULL;
+    rb_io_t *fptr;
+#ifndef HAVE_RB_IO_WAIT
+    struct timeval timerec;
+    struct timeval *tv;
+#endif
 
-    RB_IO_POINTER(io, fptr);
+    GetOpenFile(io, fptr);
     rb_io_check_readable(fptr);
 
+#ifndef HAVE_RB_IO_WAIT
+    tv = get_timeout(argc, argv, &timerec);
+#endif
     if (rb_io_read_pending(fptr)) return Qtrue;
 
+#ifndef HAVE_RB_IO_WAIT
+    if (wait_for_single_fd(fptr, RB_WAITFD_IN, tv)) {
+	return io;
+    }
+    return Qnil;
+#else
     rb_check_arity(argc, 0, 1);
     VALUE timeout = (argc == 1 ? argv[0] : Qnil);
 
     return io_wait_event(io, RUBY_IO_READABLE, timeout);
+#endif
 }
 
 /*
@@ -139,17 +197,30 @@ io_wait_readable(int argc, VALUE *argv, VALUE io)
 static VALUE
 io_wait_writable(int argc, VALUE *argv, VALUE io)
 {
-    rb_io_t *fptr = NULL;
+    rb_io_t *fptr;
+#ifndef HAVE_RB_IO_WAIT
+    struct timeval timerec;
+    struct timeval *tv;
+#endif
 
-    RB_IO_POINTER(io, fptr);
+    GetOpenFile(io, fptr);
     rb_io_check_writable(fptr);
 
+#ifndef HAVE_RB_IO_WAIT
+    tv = get_timeout(argc, argv, &timerec);
+    if (wait_for_single_fd(fptr, RB_WAITFD_OUT, tv)) {
+	return io;
+    }
+    return Qnil;
+#else
     rb_check_arity(argc, 0, 1);
     VALUE timeout = (argc == 1 ? argv[0] : Qnil);
 
     return io_wait_event(io, RUBY_IO_WRITABLE, timeout);
+#endif
 }
 
+#ifdef HAVE_RB_IO_WAIT
 /*
  * call-seq:
  *   io.wait_priority          -> true or false
@@ -173,6 +244,7 @@ io_wait_priority(int argc, VALUE *argv, VALUE io)
 
     return io_wait_event(io, RUBY_IO_PRIORITY, timeout);
 }
+#endif
 
 static int
 wait_mode_sym(VALUE mode)
@@ -228,6 +300,31 @@ wait_mode_sym(VALUE mode)
 static VALUE
 io_wait(int argc, VALUE *argv, VALUE io)
 {
+#ifndef HAVE_RB_IO_WAIT
+    rb_io_t *fptr;
+    struct timeval timerec;
+    struct timeval *tv = NULL;
+    int event = 0;
+    int i;
+
+    GetOpenFile(io, fptr);
+    for (i = 0; i < argc; ++i) {
+	if (SYMBOL_P(argv[i])) {
+	    event |= wait_mode_sym(argv[i]);
+	}
+	else {
+	    *(tv = &timerec) = rb_time_interval(argv[i]);
+	}
+    }
+    /* rb_time_interval() and might_mode() might convert the argument */
+    rb_io_check_closed(fptr);
+    if (!event) event = RB_WAITFD_IN;
+    if ((event & RB_WAITFD_IN) && rb_io_read_pending(fptr))
+	return Qtrue;
+    if (wait_for_single_fd(fptr, event, tv))
+	return io;
+    return Qnil;
+#else
     VALUE timeout = Qundef;
     rb_io_event_t events = 0;
 
@@ -264,6 +361,7 @@ io_wait(int argc, VALUE *argv, VALUE io)
     }
 
     return io_wait_event(io, events, timeout);
+#endif
 }
 
 /*
@@ -284,5 +382,7 @@ Init_wait(void)
 
     rb_define_method(rb_cIO, "wait_readable", io_wait_readable, -1);
     rb_define_method(rb_cIO, "wait_writable", io_wait_writable, -1);
+#ifdef HAVE_RB_IO_WAIT
     rb_define_method(rb_cIO, "wait_priority", io_wait_priority, -1);
+#endif
 }