diff --git a/complex.c b/complex.c
index 1aae3b6ca80b25..b3279f3e0a9e44 100644
--- a/complex.c
+++ b/complex.c
@@ -21,7 +21,8 @@ VALUE rb_cComplex;
 static ID id_abs, id_abs2, id_arg, id_cmp, id_conj, id_convert,
     id_denominator, id_divmod, id_eqeq_p, id_expt, id_fdiv,  id_floor,
     id_idiv, id_imag, id_inspect, id_negate, id_numerator, id_quo,
-    id_real, id_real_p, id_to_f, id_to_i, id_to_r, id_to_s;
+    id_real, id_real_p, id_to_f, id_to_i, id_to_r, id_to_s,
+    id_i_real, id_i_imag;
 
 #define f_boolcast(x) ((x) ? Qtrue : Qfalse)
 
@@ -1242,6 +1243,25 @@ nucomp_inspect(VALUE self)
     return s;
 }
 
+/* :nodoc: */
+static VALUE
+nucomp_dumper(VALUE self)
+{
+    return self;
+}
+
+/* :nodoc: */
+static VALUE
+nucomp_loader(VALUE self, VALUE a)
+{
+    get_dat1(self);
+
+    dat->real = rb_ivar_get(a, id_i_real);
+    dat->imag = rb_ivar_get(a, id_i_imag);
+
+    return self;
+}
+
 /* :nodoc: */
 static VALUE
 nucomp_marshal_dump(VALUE self)
@@ -1250,7 +1270,6 @@ nucomp_marshal_dump(VALUE self)
     get_dat1(self);
 
     a = rb_assoc_new(dat->real, dat->imag);
-    rb_copy_generic_ivar(a, self);
     return a;
 }
 
@@ -1258,17 +1277,11 @@ nucomp_marshal_dump(VALUE self)
 static VALUE
 nucomp_marshal_load(VALUE self, VALUE a)
 {
-    get_dat1(self);
-
-    rb_check_frozen(self);
-    rb_check_trusted(self);
-
     Check_Type(a, T_ARRAY);
     if (RARRAY_LEN(a) != 2)
 	rb_raise(rb_eArgError, "marshaled complex must have an array whose length is 2 but %ld", RARRAY_LEN(a));
-    dat->real = RARRAY_PTR(a)[0];
-    dat->imag = RARRAY_PTR(a)[1];
-    rb_copy_generic_ivar(self, a);
+    rb_ivar_set(self, id_i_real, RARRAY_PTR(a)[0]);
+    rb_ivar_set(self, id_i_imag, RARRAY_PTR(a)[1]);
     return self;
 }
 
@@ -1833,6 +1846,7 @@ float_arg(VALUE self)
 void
 Init_Complex(void)
 {
+    VALUE compat;
 #undef rb_intern
 #define rb_intern(str) rb_intern_const(str)
 
@@ -1862,6 +1876,8 @@ Init_Complex(void)
     id_to_i = rb_intern("to_i");
     id_to_r = rb_intern("to_r");
     id_to_s = rb_intern("to_s");
+    id_i_real = rb_intern("@real");
+    id_i_imag = rb_intern("@image");
 
     rb_cComplex = rb_define_class("Complex", rb_cNumeric);
 
@@ -1951,7 +1967,9 @@ Init_Complex(void)
     rb_define_method(rb_cComplex, "inspect", nucomp_inspect, 0);
 
     rb_define_method(rb_cComplex, "marshal_dump", nucomp_marshal_dump, 0);
-    rb_define_method(rb_cComplex, "marshal_load", nucomp_marshal_load, 1);
+    compat = rb_define_class_under(rb_cComplex, "compatible", rb_cObject);
+    rb_define_method(compat, "marshal_load", nucomp_marshal_load, 1);
+    rb_marshal_define_compat(rb_cComplex, compat, nucomp_dumper, nucomp_loader);
 
     /* --- */
 
diff --git a/ext/date/date_core.c b/ext/date/date_core.c
index 82d078a0dd52ba..f5e117c117f41d 100644
--- a/ext/date/date_core.c
+++ b/ext/date/date_core.c
@@ -7251,11 +7251,6 @@ d_lite_marshal_dump(VALUE self)
 		    INT2FIX(m_of(dat)),
 		    DBL2NUM(m_sg(dat)));
 
-    if (FL_TEST(self, FL_EXIVAR)) {
-	rb_copy_generic_ivar(a, self);
-	FL_SET(a, FL_EXIVAR);
-    }
-
     return a;
 }
 
@@ -7336,6 +7331,19 @@ d_lite_marshal_load(VALUE self, VALUE a)
     return self;
 }
 
+/* :nodoc: */
+static VALUE
+d_lite_old_load(VALUE klass, VALUE s)
+{
+    VALUE data = rb_marshal_load(s);
+    VALUE self = rb_obj_alloc(klass);
+    Check_Type(data, T_ARRAY);
+    if (RARRAY_LEN(data) == 2) {
+	const VALUE *ptr = RARRAY_PTR(data);
+	data = rb_ary_new3(3, ptr[0], INT2FIX(0), ptr[1]);
+    }
+    return d_lite_marshal_load(self, data);
+}
 
 /* datetime */
 
@@ -9674,6 +9682,7 @@ Init_date_core(void)
 #endif
     rb_define_method(cDate, "marshal_dump", d_lite_marshal_dump, 0);
     rb_define_method(cDate, "marshal_load", d_lite_marshal_load, 1);
+    rb_define_singleton_method(cDate, "_load", d_lite_old_load, 1);
 
     /* datetime */
 
diff --git a/rational.c b/rational.c
index c4469c809249fe..e7a296a0d1e39f 100644
--- a/rational.c
+++ b/rational.c
@@ -25,7 +25,7 @@ VALUE rb_cRational;
 
 static ID id_abs, id_cmp, id_convert, id_eqeq_p, id_expt, id_fdiv,
     id_floor, id_idiv, id_inspect, id_integer_p, id_negate, id_to_f,
-    id_to_i, id_to_s, id_truncate;
+    id_to_i, id_to_s, id_truncate, id_i_num, id_i_den;
 
 #define f_boolcast(x) ((x) ? Qtrue : Qfalse)
 
@@ -1588,6 +1588,25 @@ nurat_inspect(VALUE self)
     return s;
 }
 
+/* :nodoc: */
+static VALUE
+nurat_dumper(VALUE self)
+{
+    return self;
+}
+
+/* :nodoc: */
+static VALUE
+nurat_loader(VALUE self, VALUE a)
+{
+    get_dat1(self);
+
+    dat->num = rb_ivar_get(a, id_i_num);
+    dat->den = rb_ivar_get(a, id_i_den);
+
+    return self;
+}
+
 /* :nodoc: */
 static VALUE
 nurat_marshal_dump(VALUE self)
@@ -1596,7 +1615,6 @@ nurat_marshal_dump(VALUE self)
     get_dat1(self);
 
     a = rb_assoc_new(dat->num, dat->den);
-    rb_copy_generic_ivar(a, self);
     return a;
 }
 
@@ -1604,21 +1622,18 @@ nurat_marshal_dump(VALUE self)
 static VALUE
 nurat_marshal_load(VALUE self, VALUE a)
 {
-    get_dat1(self);
-
     rb_check_frozen(self);
     rb_check_trusted(self);
 
     Check_Type(a, T_ARRAY);
     if (RARRAY_LEN(a) != 2)
 	rb_raise(rb_eArgError, "marshaled rational must have an array whose length is 2 but %ld", RARRAY_LEN(a));
-    dat->num = RARRAY_PTR(a)[0];
-    dat->den = RARRAY_PTR(a)[1];
-    rb_copy_generic_ivar(self, a);
-
-    if (f_zero_p(dat->den))
+    if (f_zero_p(RARRAY_PTR(a)[1]))
 	rb_raise_zerodiv();
 
+    rb_ivar_set(self, id_i_num, RARRAY_PTR(a)[0]);
+    rb_ivar_set(self, id_i_den, RARRAY_PTR(a)[1]);
+
     return self;
 }
 
@@ -2295,6 +2310,7 @@ nurat_s_convert(int argc, VALUE *argv, VALUE klass)
 void
 Init_Rational(void)
 {
+    VALUE compat;
 #undef rb_intern
 #define rb_intern(str) rb_intern_const(str)
 
@@ -2315,6 +2331,8 @@ Init_Rational(void)
     id_to_i = rb_intern("to_i");
     id_to_s = rb_intern("to_s");
     id_truncate = rb_intern("truncate");
+    id_i_num = rb_intern("@numerator");
+    id_i_den = rb_intern("@denominator");
 
     rb_cRational = rb_define_class("Rational", rb_cNumeric);
 
@@ -2375,7 +2393,9 @@ Init_Rational(void)
     rb_define_method(rb_cRational, "inspect", nurat_inspect, 0);
 
     rb_define_method(rb_cRational, "marshal_dump", nurat_marshal_dump, 0);
-    rb_define_method(rb_cRational, "marshal_load", nurat_marshal_load, 1);
+    compat = rb_define_class_under(rb_cRational, "compatible", rb_cObject);
+    rb_define_method(compat, "marshal_load", nurat_marshal_load, 1);
+    rb_marshal_define_compat(rb_cRational, compat, nurat_dumper, nurat_loader);
 
     /* --- */
 
diff --git a/test/date/test_date_marshal.rb b/test/date/test_date_marshal.rb
index 4ea5565716e127..b385c0792fd8f0 100644
--- a/test/date/test_date_marshal.rb
+++ b/test/date/test_date_marshal.rb
@@ -38,4 +38,15 @@ def test_marshal
     assert_raise(RuntimeError){d.marshal_load(a)}
   end
 
+  def test_marshal_old
+    bug6652 = '[ruby-core:45891]'
+
+    data = "\004\bu:\tDate=\004\b[\bo:\rRational\a:\017@numeratori\003%\275J:\021" \
+           "@denominatori\ai\000i\003\031\025#"
+    assert_equal(Date.new(1993, 2, 24), Marshal.load(data), bug6652)
+
+    data = "\004\bu:\rDateTimeC\004\b[\bo:\rRational\a:\017@numeratorl+\bK\355B\024\003\000:\021" \
+           "@denominatori\002\030\025i\000i\003\031\025#"
+    assert_equal(DateTime.new(1993, 2, 24, 12, 34, 56), Marshal.load(data), bug6652)
+  end
 end
diff --git a/test/ruby/test_complex.rb b/test/ruby/test_complex.rb
index aa6d6a77feadba..51fb519b673dda 100644
--- a/test/ruby/test_complex.rb
+++ b/test/ruby/test_complex.rb
@@ -657,15 +657,15 @@ def test_marshal
       assert_instance_of(Complex, c2)
     end
 
-    bug3656 = '[ruby-core:31622]'
-    assert_raise(TypeError, bug3656) {
-      Complex(1,2).marshal_load(0)
-    }
-
     c = Complex(1,2)
-    c.freeze
-    assert(c.frozen?)
-    assert_raise(RuntimeError){c.marshal_load([2,3])}
+    assert_respond_to(c, :marshal_dump)
+    assert_not_respond_to(c, :marshal_load)
+  end
+
+  def test_marshal_old
+    bug6625 = '[ruby-core:45775]'
+    data = "\004\bo:\fComplex\a:\n@reali\f:\v@imagei/"
+    assert_equal(Complex(7, 42), Marshal.load(data), bug6625)
   end
 
   def test_parse
diff --git a/test/ruby/test_rational.rb b/test/ruby/test_rational.rb
index e1aafb5a0aa338..bf1bbd951721ca 100644
--- a/test/ruby/test_rational.rb
+++ b/test/ruby/test_rational.rb
@@ -827,15 +827,15 @@ def test_marshal
       Marshal.load("\x04\bU:\rRational[\ai\x06i\x05")
     }
 
-    bug3656 = '[ruby-core:31622]'
-    assert_raise(TypeError, bug3656) {
-      Rational(1,2).marshal_load(0)
-    }
-
     c = Rational(1,2)
-    c.freeze
-    assert(c.frozen?)
-    assert_raise(RuntimeError){c.marshal_load([2,3])}
+    assert_respond_to(c, :marshal_dump)
+    assert_not_respond_to(c, :marshal_load)
+  end
+
+  def test_marshal_old
+    bug6625 = '[ruby-core:45775]'
+    data = "\004\bo:\rRational\a:\021@denominatori\035:\017@numeratori\f"
+    assert_equal(Rational(7, 24), Marshal.load(data), bug6625)
   end
 
   def test_parse