diff --git a/ext/-test-/marshal/usr/usrmarshal.c b/ext/-test-/marshal/usr/usrmarshal.c
index b30bd52c13..056f0326c0 100644
--- a/ext/-test-/marshal/usr/usrmarshal.c
+++ b/ext/-test-/marshal/usr/usrmarshal.c
@@ -1,23 +1,38 @@
 #include <ruby.h>
 
+static size_t
+usr_size(const void *ptr)
+{
+    return sizeof(int);
+}
+
+static const rb_data_type_t usrmarshal_type = {
+    "UsrMarshal",
+    {0, RUBY_DEFAULT_FREE, usr_size,},
+    NULL, NULL,
+    RUBY_TYPED_FREE_IMMEDIATELY|RUBY_TYPED_WB_PROTECTED,
+};
+
 static VALUE
 usr_alloc(VALUE klass)
 {
     int *p;
-    return Data_Make_Struct(klass, int, 0, RUBY_DEFAULT_FREE, p);
+    return TypedData_Make_Struct(klass, int, &usrmarshal_type, p);
 }
 
 static VALUE
 usr_init(VALUE self, VALUE val)
 {
-    *(int *)DATA_PTR(self) = NUM2INT(val);
+    int *ptr = Check_TypedStruct(self, &usrmarshal_type);
+    *ptr = NUM2INT(val);
     return self;
 }
 
 static VALUE
 usr_value(VALUE self)
 {
-    int val = *(int *)DATA_PTR(self);
+    int *ptr = Check_TypedStruct(self, &usrmarshal_type);
+    int val = *ptr;
     return INT2NUM(val);
 }
 
diff --git a/ext/-test-/st/numhash/numhash.c b/ext/-test-/st/numhash/numhash.c
index d4dbd1a0ce..a903edd541 100644
--- a/ext/-test-/st/numhash/numhash.c
+++ b/ext/-test-/st/numhash/numhash.c
@@ -7,16 +7,29 @@ numhash_free(void *ptr)
     if (ptr) st_free_table(ptr);
 }
 
+static size_t
+numhash_memsize(const void *ptr)
+{
+    return ptr ? st_memsize(ptr) : 0;
+}
+
+static const rb_data_type_t numhash_type = {
+    "numhash",
+    {0, numhash_free, numhash_memsize,},
+    NULL, NULL,
+    RUBY_TYPED_FREE_IMMEDIATELY|RUBY_TYPED_WB_PROTECTED,
+};
+
 static VALUE
 numhash_alloc(VALUE klass)
 {
-    return Data_Wrap_Struct(klass, 0, numhash_free, 0);
+    return TypedData_Wrap_Struct(klass, &numhash_type, 0);
 }
 
 static VALUE
 numhash_init(VALUE self)
 {
-    st_table *tbl = (st_table *)DATA_PTR(self);
+    st_table *tbl = (st_table *)Check_TypedStruct(self, &numhash_type);
     if (tbl) st_free_table(tbl);
     DATA_PTR(self) = st_init_numtable();
     return self;
@@ -26,8 +39,9 @@ static VALUE
 numhash_aref(VALUE self, VALUE key)
 {
     st_data_t data;
+    st_table *tbl = (st_table *)Check_TypedStruct(self, &numhash_type);
     if (!SPECIAL_CONST_P(key)) rb_raise(rb_eArgError, "not a special const");
-    if (st_lookup((st_table *)DATA_PTR(self), (st_data_t)key, &data))
+    if (st_lookup(tbl, (st_data_t)key, &data))
 	return (VALUE)data;
     return Qnil;
 }
@@ -35,9 +49,10 @@ numhash_aref(VALUE self, VALUE key)
 static VALUE
 numhash_aset(VALUE self, VALUE key, VALUE data)
 {
+    st_table *tbl = (st_table *)Check_TypedStruct(self, &numhash_type);
     if (!SPECIAL_CONST_P(key)) rb_raise(rb_eArgError, "not a special const");
     if (!SPECIAL_CONST_P(data)) rb_raise(rb_eArgError, "not a special const");
-    st_insert((st_table *)DATA_PTR(self), (st_data_t)key, (st_data_t)data);
+    st_insert(tbl, (st_data_t)key, (st_data_t)data);
     return self;
 }
 
@@ -53,7 +68,7 @@ numhash_i(st_data_t key, st_data_t value, st_data_t arg)
 static VALUE
 numhash_each(VALUE self)
 {
-    st_table *table = DATA_PTR(self);
+    st_table *table = (st_table *)Check_TypedStruct(self, &numhash_type);
     st_data_t data = (st_data_t)self;
     return st_foreach_check(table, numhash_i, data, data) ? Qtrue : Qfalse;
 }
@@ -76,7 +91,8 @@ update_func(st_data_t *key, st_data_t *value, st_data_t arg, int existing)
 static VALUE
 numhash_update(VALUE self, VALUE key)
 {
-    if (st_update((st_table *)DATA_PTR(self), (st_data_t)key, update_func, 0))
+    st_table *table = (st_table *)Check_TypedStruct(self, &numhash_type);
+    if (st_update(table, (st_data_t)key, update_func, 0))
 	return Qtrue;
     else
 	return Qfalse;
@@ -91,14 +107,16 @@ numhash_update(VALUE self, VALUE key)
 static VALUE
 numhash_size(VALUE self)
 {
-    return ST2NUM(((st_table *)DATA_PTR(self))->num_entries);
+    st_table *table = (st_table *)Check_TypedStruct(self, &numhash_type);
+    return ST2NUM(table->num_entries);
 }
 
 static VALUE
 numhash_delete_safe(VALUE self, VALUE key)
 {
+    st_table *table = (st_table *)Check_TypedStruct(self, &numhash_type);
     st_data_t val, k = (st_data_t)key;
-    if (st_delete_safe((st_table *)DATA_PTR(self), &k, &val, (st_data_t)self)) {
+    if (st_delete_safe(table, &k, &val, (st_data_t)self)) {
 	return val;
     }
     return Qnil;
diff --git a/gc.c b/gc.c
index 5ee5beea26..ade6a7dda4 100644
--- a/gc.c
+++ b/gc.c
@@ -31,6 +31,8 @@
 #include <sys/types.h>
 #include <assert.h>
 
+#undef rb_data_object_alloc
+
 #ifndef __has_feature
 # define __has_feature(x) 0
 #endif
diff --git a/include/ruby/ruby.h b/include/ruby/ruby.h
index 6a3949ab8e..59c2d54756 100644
--- a/include/ruby/ruby.h
+++ b/include/ruby/ruby.h
@@ -973,7 +973,23 @@ struct RTypedData {
 */
 typedef void (*RUBY_DATA_FUNC)(void*);
 
+#ifndef RUBY_DEPRECATE_DATA_WRAP_STRUCT
+# ifdef RUBY_EXPORT
+#   define RUBY_DEPRECATE_DATA_WRAP_STRUCT 1
+# else
+#   define RUBY_DEPRECATE_DATA_WRAP_STRUCT 0
+# endif
+#endif
 VALUE rb_data_object_alloc(VALUE,void*,RUBY_DATA_FUNC,RUBY_DATA_FUNC);
+#if RUBY_DEPRECATE_DATA_WRAP_STRUCT
+DEPRECATED(static inline VALUE rb_data_object_alloc_deprecated(VALUE,void*,RUBY_DATA_FUNC,RUBY_DATA_FUNC));
+static inline VALUE
+rb_data_object_alloc_deprecated(VALUE klass, void *ptr, RUBY_DATA_FUNC mark, RUBY_DATA_FUNC free)
+{
+    return rb_data_object_alloc(klass, ptr, mark, free);
+}
+#define rb_data_object_alloc rb_data_object_alloc_deprecated
+#endif
 VALUE rb_data_typed_object_alloc(VALUE klass, void *datap, const rb_data_type_t *);
 int rb_typeddata_inherited_p(const rb_data_type_t *child, const rb_data_type_t *parent);
 int rb_typeddata_is_kind_of(VALUE, const rb_data_type_t *);
diff --git a/marshal.c b/marshal.c
index 598f90f187..26fd0bcc0b 100644
--- a/marshal.c
+++ b/marshal.c
@@ -28,6 +28,8 @@
 #include <ieeefp.h>
 #endif
 
+#undef rb_data_object_alloc
+
 #define BITSPERSHORT (2*CHAR_BIT)
 #define SHORTMASK ((1<<BITSPERSHORT)-1)
 #define SHORTDN(x) RSHIFT((x),BITSPERSHORT)