diff --git a/compiler/ml/ast_untagged_variants.ml b/compiler/ml/ast_untagged_variants.ml
index ab53f3961e..ec8e84ac8c 100644
--- a/compiler/ml/ast_untagged_variants.ml
+++ b/compiler/ml/ast_untagged_variants.ml
@@ -166,8 +166,8 @@ let type_to_instanceof_backed_obj (t : Types.type_expr) =
   | Tconstr (path, _, _) when Path.same path Predef.path_array -> Some Array
   | Tconstr (path, _, _) -> (
     match Path.name path with
-    | "Js_date.t" -> Some Date
-    | "Js_re.t" -> Some RegExp
+    | "CoreTypes.date" -> Some Date
+    | "CoreTypes.regExp" -> Some RegExp
     | "Js_file.t" -> Some File
     | "Js_blob.t" -> Some Blob
     | _ -> None)
diff --git a/lib/es6/CoreTypes.js b/lib/es6/CoreTypes.js
new file mode 100644
index 0000000000..ae1b9f17e6
--- /dev/null
+++ b/lib/es6/CoreTypes.js
@@ -0,0 +1 @@
+/* This output is empty. Its source's type definitions, externals and/or unused code got optimized away. */
diff --git a/lib/js/CoreTypes.js b/lib/js/CoreTypes.js
new file mode 100644
index 0000000000..ae1b9f17e6
--- /dev/null
+++ b/lib/js/CoreTypes.js
@@ -0,0 +1 @@
+/* This output is empty. Its source's type definitions, externals and/or unused code got optimized away. */
diff --git a/packages/artifacts.txt b/packages/artifacts.txt
index ac398baaae..4c27c7de15 100644
--- a/packages/artifacts.txt
+++ b/packages/artifacts.txt
@@ -76,6 +76,7 @@ lib/es6/BigInt64Array.js
 lib/es6/BigUint64Array.js
 lib/es6/Char.js
 lib/es6/Console.js
+lib/es6/CoreTypes.js
 lib/es6/DataView.js
 lib/es6/Date.js
 lib/es6/Dict.js
@@ -244,6 +245,7 @@ lib/js/BigInt64Array.js
 lib/js/BigUint64Array.js
 lib/js/Char.js
 lib/js/Console.js
+lib/js/CoreTypes.js
 lib/js/DataView.js
 lib/js/Date.js
 lib/js/Dict.js
@@ -649,6 +651,10 @@ lib/ocaml/Console.cmt
 lib/ocaml/Console.cmti
 lib/ocaml/Console.res
 lib/ocaml/Console.resi
+lib/ocaml/CoreTypes.cmi
+lib/ocaml/CoreTypes.cmj
+lib/ocaml/CoreTypes.cmt
+lib/ocaml/CoreTypes.res
 lib/ocaml/DataView.cmi
 lib/ocaml/DataView.cmj
 lib/ocaml/DataView.cmt
diff --git a/runtime/CoreTypes.res b/runtime/CoreTypes.res
new file mode 100644
index 0000000000..768f941866
--- /dev/null
+++ b/runtime/CoreTypes.res
@@ -0,0 +1,3 @@
+type date
+
+type regExp
diff --git a/runtime/Date.res b/runtime/Date.res
index 925afcc190..0f1d424af5 100644
--- a/runtime/Date.res
+++ b/runtime/Date.res
@@ -1,4 +1,4 @@
-type t = Js.Date.t
+type t = CoreTypes.date
 
 type msSinceEpoch = float
 
diff --git a/runtime/Date.resi b/runtime/Date.resi
index f0d975ba1a..8e0c14f65b 100644
--- a/runtime/Date.resi
+++ b/runtime/Date.resi
@@ -5,7 +5,7 @@
 /**
 A type representing a JavaScript date.
 */
-type t = Js.Date.t
+type t = CoreTypes.date
 
 /**
 Time, in milliseconds, since / until the UNIX epoch (January 1, 1970 00:00:00 UTC).
diff --git a/runtime/Js_date.res b/runtime/Js_date.res
index 2a7b6be24b..7d2fd8ea0c 100644
--- a/runtime/Js_date.res
+++ b/runtime/Js_date.res
@@ -29,7 +29,7 @@ on MDN.) JavaScript stores dates as the number of milliseconds since the UNIX
 *epoch*, midnight 1 January 1970, UTC.
 */
 
-type t
+type t = CoreTypes.date
 
 @send
 /**
diff --git a/runtime/Js_re.res b/runtime/Js_re.res
index 05e46ec64a..2253b6c4b5 100644
--- a/runtime/Js_re.res
+++ b/runtime/Js_re.res
@@ -31,7 +31,7 @@ and subsequent uses will continue the search from the previous [`lastIndex`]().
 */
 
 /** The RegExp object. */
-type t
+type t = CoreTypes.regExp
 
 /** The result of a executing a RegExp on a string. */
 type result
diff --git a/runtime/Pervasives.res b/runtime/Pervasives.res
index 8f05695ddc..d4c6f4d8e9 100644
--- a/runtime/Pervasives.res
+++ b/runtime/Pervasives.res
@@ -1,15 +1,12 @@
-/**
-   Since [others] depend on this file, its public mli files **should not
-   export types** introduced here, otherwise it would cause 
-   conflicts here.
+/* Core type aliases */
 
-   If the type exported here is also exported in modules from others,
-   you will get a type not equivalent.
-*/
-@deprecated("Do not use. This will be removed in v13")
-external /* Internal */
+type date = CoreTypes.date
+type regExp = CoreTypes.regExp
 
-__unsafe_cast: 'a => 'b = "%identity"
+/* Internal */
+
+@deprecated("Do not use. This will be removed in v13")
+external __unsafe_cast: 'a => 'b = "%identity"
 
 /* Exceptions */
 
diff --git a/runtime/RegExp.res b/runtime/RegExp.res
index 9f19af81ab..6ac623a935 100644
--- a/runtime/RegExp.res
+++ b/runtime/RegExp.res
@@ -1,4 +1,4 @@
-type t = Js.Re.t
+type t = CoreTypes.regExp
 
 module Result = {
   type t = array<option<string>>
diff --git a/tests/gentype_tests/typescript-react-example/package-lock.json b/tests/gentype_tests/typescript-react-example/package-lock.json
index 3d1726bcb8..090c2be357 100644
--- a/tests/gentype_tests/typescript-react-example/package-lock.json
+++ b/tests/gentype_tests/typescript-react-example/package-lock.json
@@ -22,7 +22,7 @@
     },
     "../../..": {
       "name": "rescript",
-      "version": "12.0.0-alpha.4",
+      "version": "12.0.0-alpha.5",
       "dev": true,
       "hasInstallScript": true,
       "license": "SEE LICENSE IN LICENSE",
diff --git a/tests/gentype_tests/typescript-react-example/src/nested/Types.res b/tests/gentype_tests/typescript-react-example/src/nested/Types.res
index 54fa80803c..c7d074824d 100644
--- a/tests/gentype_tests/typescript-react-example/src/nested/Types.res
+++ b/tests/gentype_tests/typescript-react-example/src/nested/Types.res
@@ -122,7 +122,7 @@ type instantiateTypeParameter = ocaml_array<someRecord>
 @genType @genType.as("Vector")
 type vector<'a> = ('a, 'a)
 
-@genType type date = Js.Date.t
+@genType type date = Date.t
 
 @genType let currentTime = Js.Date.make()
 
diff --git a/tests/syntax_tests/data/idempotency/pupilfirst/shared/DateTime.res b/tests/syntax_tests/data/idempotency/pupilfirst/shared/DateTime.res
index b902ba4261..b0b83d9bcd 100644
--- a/tests/syntax_tests/data/idempotency/pupilfirst/shared/DateTime.res
+++ b/tests/syntax_tests/data/idempotency/pupilfirst/shared/DateTime.res
@@ -1,4 +1,4 @@
-type t = Js.Date.t
+type t = Date.t
 
 @val @module("date-fns")
 external dateFormat: (t, string) => string = "format"
diff --git a/tests/syntax_tests/data/idempotency/pupilfirst/shared/DateTime.resi b/tests/syntax_tests/data/idempotency/pupilfirst/shared/DateTime.resi
index 0bcbd37e00..1dcf30fdea 100644
--- a/tests/syntax_tests/data/idempotency/pupilfirst/shared/DateTime.resi
+++ b/tests/syntax_tests/data/idempotency/pupilfirst/shared/DateTime.resi
@@ -1,4 +1,4 @@
-type t = Js.Date.t
+type t = Date.t
 
 type format =
   | OnlyDate