diff --git a/ChangeLog b/ChangeLog
index 8333a38429..b452e01636 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Fri Jun 19 17:04:59 2009  Yukihiro Matsumoto  <matz@ruby-lang.org>
+
+	* numeric.c (flo_cmp): should always return nil for NaN.
+
+	* numeric.c (flo_cmp): handle infinite value specially using
+	  infinite? method internally.  [ruby-dev:38681]
+
 Fri Jun 19 09:28:45 2009  Tadayoshi Funaba  <tadf@dotrb.org>
 
 	* numeric.c (*_numerator,*_denominator): moved to rational.c.
diff --git a/numeric.c b/numeric.c
index 6ff074e04e..8ba7d3fd7e 100644
--- a/numeric.c
+++ b/numeric.c
@@ -937,6 +937,7 @@ flo_cmp(VALUE x, VALUE y)
     double a, b;
 
     a = RFLOAT_VALUE(x);
+    if (isnan(a)) return Qnil;
     switch (TYPE(y)) {
       case T_FIXNUM:
 	b = (double)FIX2LONG(y);
@@ -955,6 +956,11 @@ flo_cmp(VALUE x, VALUE y)
 	break;
 
       default:
+	if (isinf(a) && (!rb_respond_to(y, rb_intern("infinite?")) ||
+			 !RTEST(rb_funcall(y, rb_intern("infinite?"), 0, 0)))) {
+	    if (a > 0.0) return INT2FIX(1);
+	    return INT2FIX(-1);
+	}
 	return rb_num_coerce_cmp(x, y, rb_intern("<=>"));
     }
     return rb_dbl_cmp(a, b);