diff --git a/CHANGELOG.md b/CHANGELOG.md
index fc125acd..23dc8533 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,14 @@
 
 ## Next version
 
+### API changes
+
+- Add `Math.Int.floor` and `Math.Int.random`, https://github.com/rescript-association/rescript-core/pull/156
+
+### Documentation
+
+- Docstrings for `Math.Int.floor` and `Math.Int.random`. https://github.com/rescript-association/rescript-core/pull/156
+
 ## 0.5.0
 
 ### API changes
@@ -96,4 +104,4 @@
 - Docstrings for `Date`. https://github.com/rescript-association/rescript-core/pull/61
 - Docstrings for `Float`. https://github.com/rescript-association/rescript-core/pull/54
 - Docstrings for `String`. https://github.com/rescript-association/rescript-core/pull/27
-- Docstrings from `Array`. https://github.com/rescript-association/rescript-core/pull/78
+- Docstrings for `Array`. https://github.com/rescript-association/rescript-core/pull/78
diff --git a/src/Core__Math.mjs b/src/Core__Math.mjs
index 87e83ffa..7f46c580 100644
--- a/src/Core__Math.mjs
+++ b/src/Core__Math.mjs
@@ -3,7 +3,19 @@
 
 var Constants = {};
 
-var Int = {};
+function floor(f) {
+  return Math.floor(f) | 0;
+}
+
+function random(min, max) {
+  var f = Math.random() * (max - min | 0);
+  return (Math.floor(f) | 0) + min | 0;
+}
+
+var Int = {
+  floor: floor,
+  random: random
+};
 
 export {
   Constants ,
diff --git a/src/Core__Math.res b/src/Core__Math.res
index a468332b..38ddc153 100644
--- a/src/Core__Math.res
+++ b/src/Core__Math.res
@@ -9,18 +9,6 @@ module Constants = {
   @val external sqrt2: float = "Math.SQRT2"
 }
 
-module Int = {
-  @val external abs: int => int = "Math.abs"
-  @val external clz32: int => int = "Math.clz32"
-  @val external imul: (int, int) => int = "Math.imul"
-  @val external min: (int, int) => int = "Math.min"
-  @variadic @val external minMany: array<int> => int = "Math.min"
-  @val external max: (int, int) => int = "Math.max"
-  @variadic @val external maxMany: array<int> => int = "Math.max"
-  @val external pow: (int, ~exp: int) => int = "Math.pow"
-  @val external sign: int => int = "Math.sign"
-}
-
 @val external abs: float => float = "Math.abs"
 @val external acos: float => float = "Math.acos"
 @val external acosh: float => float = "Math.acosh"
@@ -57,3 +45,18 @@ module Int = {
 @val external tan: float => float = "Math.tan"
 @val external tanh: float => float = "Math.tanh"
 @val external trunc: float => float = "Math.trunc"
+
+module Int = {
+  @val external abs: int => int = "Math.abs"
+  @val external clz32: int => int = "Math.clz32"
+  @val external imul: (int, int) => int = "Math.imul"
+  @val external min: (int, int) => int = "Math.min"
+  @variadic @val external minMany: array<int> => int = "Math.min"
+  @val external max: (int, int) => int = "Math.max"
+  @variadic @val external maxMany: array<int> => int = "Math.max"
+  @val external pow: (int, ~exp: int) => int = "Math.pow"
+  @val external sign: int => int = "Math.sign"
+  let floor: float => int = f => f->floor->Core__Float.toInt
+  let random: (int, int) => int = (min, max) =>
+    floor(random() *. Core__Int.toFloat(max - min)) + min
+}
diff --git a/src/Core__Math.resi b/src/Core__Math.resi
index eaecfb46..a9f39643 100644
--- a/src/Core__Math.resi
+++ b/src/Core__Math.resi
@@ -276,6 +276,39 @@ module Int: {
   */
   @val
   external sign: int => int = "Math.sign"
+
+  /**
+  floor(v) returns the largest `int` less than or equal to the argument; 
+  the result is pinned to the range of the `int` data type: -2147483648 to 2147483647. 
+  See [`Math.floor`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/floor)
+  on MDN.
+
+  ## Examples
+
+  ```rescript
+  Math.Int.floor(3.7) == 3
+  Math.Int.floor(3.0) == 3
+  Math.Int.floor(-3.1) == -4
+  Math.Int.floor(-1.0e15) == -2147483648
+  Math.Int.floor(1.0e15) == 2147483647
+  ```
+  */
+  let floor: float => int
+
+  /**
+  `random(minVal, maxVal)` returns a random integer number in the half-closed interval [minVal, maxVal).
+   See [`Math.random`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/random)
+  on MDN.
+
+  ## Examples
+
+  ```rescript
+  Math.Int.random(2, 5) == 4
+  Math.Int.random(505, 2000) == 1276
+  Math.Int.random(-7, -2) == -4
+  ```
+  */
+  let random: (int, int) => int
 }
 
 /**