diff --git a/src/number/number.util.test.ts b/src/number/number.util.test.ts
index 87302439..8794f995 100644
--- a/src/number/number.util.test.ts
+++ b/src/number/number.util.test.ts
@@ -27,6 +27,7 @@ test.each([
   [2, 2, 1, false],
   [2, 2, 2, false],
   [2, Number.NEGATIVE_INFINITY, 3, true],
+  ['2020-01-03', '2020-01-01', '2020-01-05', true],
 ])('_isBetween(%s, %s, %s) === %s', (n, min, max, result) => {
   expect(_isBetween(n, min, max)).toBe(result)
 })
diff --git a/src/number/number.util.ts b/src/number/number.util.ts
index 0c30280f..717737ce 100644
--- a/src/number/number.util.ts
+++ b/src/number/number.util.ts
@@ -34,11 +34,14 @@ export function _runLessOften(percent: number): boolean {
  * _isBetween(3, 1, 5) // true
  * _isBetween(5, 1, 5) // false
  * _isBetween(7, 1, 5) // false
+ *
+ * Also works with strings:
+ * _isBetween('2020-01-03', '2020-01-01', '2020-01-05') // true
  */
-export function _isBetween(
-  x: number,
-  min: number,
-  max: number,
+export function _isBetween<T extends number | string>(
+  x: T,
+  min: T,
+  max: T,
   incl: Inclusiveness = '[)',
 ): boolean {
   if (incl === '[)') {
@@ -48,7 +51,6 @@ export function _isBetween(
   } else if (incl === '(]') {
     return x > min && x <= max
   }
-  // ()
   return x > min && x < max
 }