diff --git a/packages/array-partition/index.d.ts b/packages/array-partition/index.d.ts
index d6d8e6597..906466946 100644
--- a/packages/array-partition/index.d.ts
+++ b/packages/array-partition/index.d.ts
@@ -11,4 +11,6 @@
  * partition(['a', 1, 2, 'b'], x => typeof x == 'string');
  * // => [['a', 'b'], [1, 2]]
  */
-export default function partition<T>(arr: T[], resolver: (arg: T) => boolean): [T[], T[]]
+declare function partition<T, S extends T>(arr: T[], resolver: (arg: T) => arg is S): [S[], Exclude<T, S>[]];
+declare function partition<T>(arr: T[], resolver: (arg: T) => boolean): [T[], T[]]
+export default partition;
diff --git a/packages/array-partition/index.tests.ts b/packages/array-partition/index.tests.ts
index 2dd9706c8..1937ecde5 100644
--- a/packages/array-partition/index.tests.ts
+++ b/packages/array-partition/index.tests.ts
@@ -2,9 +2,12 @@ import partition from './index';
 
 // OK
 const test1: [number[], number[]] = partition([1, 5, 2, 4, 3], n => n > 3);
-const test2: [string[], number[]] = partition(['a', 2, 3, '3'], x => typeof x == 'string') as [string[], number[]]; //if you know better than typescript
+const test2: [string[], number[]] = partition(['a', 2, 3, '3'], (x): x is string => {
+  return typeof x === 'string';
+});
 const test3: [number[], number[]] = partition([1, 2, 3, 4], x => typeof x == 'string');
 const test4: [unknown[], unknown[]] = partition([], n => n > 3); // [[], []]
+const test5: [boolean[], number[]] = partition([1, true, 2, 3, true], isBoolean);
 
 // Not OK
 // @ts-expect-error
@@ -19,3 +22,7 @@ partition(null, n => n > 1);
 partition(undefined, n => n > 1);
 // @ts-expect-error
 partition([1, 5, 2, 4, 3], n => n > 3, "a");
+
+function isBoolean(x: unknown): x is boolean {
+  return typeof x === 'boolean';
+}