diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9b7f3989..870278d6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,7 @@
 
 - Optimize compare and equal functions. https://github.com/rescript-association/rescript-core/pull/238
 - Add `make` and `done` + `value` functions to `AsyncIterator`. https://github.com/rescript-association/rescript-core/pull/243
+- Int: Add bitwise functions from Pervasives. https://github.com/rescript-association/rescript-core/pull/245
 
 ## 1.5.2
 
diff --git a/src/Core__Int.mjs b/src/Core__Int.mjs
index 7900b26f..0cf704a2 100644
--- a/src/Core__Int.mjs
+++ b/src/Core__Int.mjs
@@ -64,6 +64,14 @@ function clamp(min, max, value) {
   }
 }
 
+function lnot(x) {
+  return x ^ -1;
+}
+
+var Bitwise = {
+  lnot: lnot
+};
+
 var Constants = {
   minValue: -2147483648,
   maxValue: 2147483647
@@ -75,5 +83,6 @@ export {
   range ,
   rangeWithOptions ,
   clamp ,
+  Bitwise ,
 }
 /* No side effect */
diff --git a/src/Core__Int.res b/src/Core__Int.res
index b1a0f22e..462af4a7 100644
--- a/src/Core__Int.res
+++ b/src/Core__Int.res
@@ -90,3 +90,15 @@ let clamp = (~min=?, ~max=?, value): int => {
   | _ => value
   }
 }
+
+module Bitwise = {
+  external land: (int, int) => int = "%andint"
+  external lor: (int, int) => int = "%orint"
+  external lxor: (int, int) => int = "%xorint"
+
+  external lsl: (int, int) => int = "%lslint"
+  external lsr: (int, int) => int = "%lsrint"
+  external asr: (int, int) => int = "%asrint"
+
+  let lnot = x => lxor(x, -1)
+}
diff --git a/src/Core__Int.resi b/src/Core__Int.resi
index bb74f75a..bab41ce0 100644
--- a/src/Core__Int.resi
+++ b/src/Core__Int.resi
@@ -387,3 +387,82 @@ Int.clamp(42, ~min=50, ~max=40) == 50
 ```
 */
 let clamp: (~min: int=?, ~max: int=?, int) => int
+
+module Bitwise: {
+  /**
+  `land(n1, n2)` calculates the bitwise logical AND of two integers.
+
+  ## Examples
+
+  ```rescript
+  Int.Bitwise.land(7, 4) == 4
+  ```
+  */
+  external land: (int, int) => int = "%andint"
+
+  /**
+  `lor(n1, n2)` calculates the bitwise logical OR of two integers.
+
+  ## Examples
+
+  ```rescript
+  Int.Bitwise.lor(7, 4) == 7
+  ```
+  */
+  external lor: (int, int) => int = "%orint"
+
+  /**
+  `lxor(n1, n2)` calculates the bitwise logical XOR of two integers.
+
+  ## Examples
+
+  ```rescript
+  Int.Bitwise.lxor(7, 4) == 3
+  ```
+  */
+  external lxor: (int, int) => int = "%xorint"
+
+  /**
+  `lnot(n)` calculates the bitwise logical NOT of an integer.
+
+  ## Examples
+
+  ```rescript
+  Int.Bitwise.lnot(2) == -3
+  ```
+  */
+  let lnot: int => int
+
+  /**
+  `lsl(n, length)` calculates the bitwise logical left shift of an integer `n` by `length`.
+
+  ## Examples
+
+  ```rescript
+  Int.Bitwise.lsl(4, 1) == 8
+  ```
+  */
+  external lsl: (int, int) => int = "%lslint"
+
+  /**
+  `lsr(n, length)` calculates the bitwise logical right shift of an integer `n` by `length`.
+
+  ## Examples
+
+  ```rescript
+  Int.Bitwise.lsr(8, 1) == 4
+  ```
+  */
+  external lsr: (int, int) => int = "%lsrint"
+
+  /**
+  `asr(n, length)` calculates the bitwise arithmetic right shift of an integer `n` by `length`.
+
+  ## Examples
+
+  ```rescript
+  Int.Bitwise.asr(4, 1) == 2
+  ```
+  */
+  external asr: (int, int) => int = "%asrint"
+}