diff --git a/ext/date/date_core.c b/ext/date/date_core.c
index 45c136c..a79ed87 100644
--- a/ext/date/date_core.c
+++ b/ext/date/date_core.c
@@ -2129,6 +2129,19 @@ jd_to_nth_kday(VALUE jd, double sg,
 }
 #endif
 
+inline static int
+gregorian_end_of_period_p(int y)
+{
+    return (y + 4712 + 1) == CM_PERIOD_GCY;
+}
+
+inline static void
+increment_period(VALUE *nth, int *ry)
+{
+    *nth = f_add(*nth, INT2FIX(1));
+    *ry -= CM_PERIOD_GCY;
+}
+
 static int
 valid_ordinal_p(VALUE y, int d, double sg,
 		VALUE *nth, int *ry,
@@ -2154,17 +2167,28 @@ valid_ordinal_p(VALUE y, int d, double sg,
     }
     else {
 	decode_year(y, style, nth, ry);
+	if ((d > 327) && gregorian_end_of_period_p(*ry))
+	    increment_period(nth, ry);
 	r = c_valid_ordinal_p(*ry, d, style, rd, rjd, ns);
     }
     return r;
 }
 
+inline static void
+ensure_gregorian_civil_period(VALUE *nth, int *ry, int m, int d)
+{
+    if ((m == 12 || (m == 11 && d > 23)) && gregorian_end_of_period_p(*ry)) {
+        increment_period(nth, ry);
+    }
+}
+
 static int
 valid_gregorian_p(VALUE y, int m, int d,
 		  VALUE *nth, int *ry,
 		  int *rm, int *rd)
 {
     decode_year(y, -1, nth, ry);
+    ensure_gregorian_civil_period(nth, ry, m, d);
     return c_valid_gregorian_p(*ry, m, d, rm, rd);
 }
 
@@ -2193,8 +2217,10 @@ valid_civil_p(VALUE y, int m, int d, double sg,
     }
     else {
 	decode_year(y, style, nth, ry);
-	if (style < 0)
+	if (style < 0) {
+	    ensure_gregorian_civil_period(nth, ry, m, d);
 	    r = c_valid_gregorian_p(*ry, m, d, rm, rd);
+	}
 	else
 	    r = c_valid_julian_p(*ry, m, d, rm, rd);
 	if (!r)
@@ -2229,6 +2255,8 @@ valid_commercial_p(VALUE y, int w, int d, double sg,
     }
     else {
 	decode_year(y, style, nth, ry);
+	if ((w > 47) && gregorian_end_of_period_p(*ry))
+	    increment_period(nth, ry);
 	r = c_valid_commercial_p(*ry, w, d, style, rw, rd, rjd, ns);
     }
     return r;
@@ -3617,6 +3645,7 @@ date_s_today(int argc, VALUE *argv, VALUE klass)
     d = tm.tm_mday;
 
     decode_year(INT2FIX(y), -1, &nth, &ry);
+    ensure_gregorian_civil_period(&nth, &ry, m, d);
 
     ret = d_simple_new_internal(klass,
 				nth, 0,
@@ -7811,6 +7840,7 @@ datetime_s_now(int argc, VALUE *argv, VALUE klass)
     }
 
     decode_year(INT2FIX(y), -1, &nth, &ry);
+    ensure_gregorian_civil_period(&nth, &ry, m, d);
 
     ret = d_complex_new_internal(klass,
 				 nth, 0,
@@ -8541,6 +8571,7 @@ time_to_date(VALUE self)
     d = FIX2INT(f_mday(self));
 
     decode_year(y, -1, &nth, &ry);
+    ensure_gregorian_civil_period(&nth, &ry, m, d);
 
     ret = d_simple_new_internal(cDate,
 				nth, 0,
@@ -8580,6 +8611,7 @@ time_to_datetime(VALUE self)
     of = FIX2INT(f_utc_offset(self));
 
     decode_year(y, -1, &nth, &ry);
+    ensure_gregorian_civil_period(&nth, &ry, m, d);
 
     ret = d_complex_new_internal(cDateTime,
 				 nth, 0,
diff --git a/test/date/test_date_arith.rb b/test/date/test_date_arith.rb
index 745ddbd..53aa4ea 100644
--- a/test/date/test_date_arith.rb
+++ b/test/date/test_date_arith.rb
@@ -80,6 +80,10 @@ class TestDateArith < Test::Unit::TestCase
 		     Date.new(2001,1,17, Date::GREGORIAN)))
     assert_equal(0, (DateTime.new(2001,1,4,0,0,0,0,Date::JULIAN) <=>
 		     DateTime.new(2001,1,17,0,0,0,0,Date::GREGORIAN)))
+
+    assert_equal(0, (Date.jd(0) <=> Date.civil(-4713, 11, 24, Date::GREGORIAN)))
+    assert_equal(0, (Date.jd(213447717) <=> Date.civil(579687, 11, 24)))
+    assert_equal(0, (Date.jd(-213447717) <=> Date.civil(-589113, 11, 24, Date::GREGORIAN)))
   end
 
   def test_prev