diff --git a/.changeset/fix-autosize-position-fixed.md b/.changeset/fix-autosize-position-fixed.md
new file mode 100644
index 000000000..5c96c95f4
--- /dev/null
+++ b/.changeset/fix-autosize-position-fixed.md
@@ -0,0 +1,5 @@
+---
+"@tabler/core": patch
+---
+
+Fixed autosize not resizing a `position: fixed` textarea.
diff --git a/core/js/src/autosize.ts b/core/js/src/autosize.ts
index e71a908eb..7b5fbf2e1 100644
--- a/core/js/src/autosize.ts
+++ b/core/js/src/autosize.ts
@@ -92,7 +92,7 @@ class Autosize extends BaseComponent {
   // Public
   update(): void {
     const element = this._element
-    if (!element.isConnected || element.offsetParent === null) {
+    if (!element.isConnected || element.getClientRects().length === 0) {
       return
     }
 
diff --git a/core/js/tests/unit/autosize.spec.ts b/core/js/tests/unit/autosize.spec.ts
index b28168987..cc61e5e85 100644
--- a/core/js/tests/unit/autosize.spec.ts
+++ b/core/js/tests/unit/autosize.spec.ts
@@ -85,6 +85,16 @@ describe('Autosize', () => {
 
       expect(height()).toBe(46)
     })
+
+    it('should still update a position: fixed field', () => {
+      textarea().style.position = 'fixed'
+      const instance = new Autosize(textarea())
+
+      textarea().value = lines(3)
+      instance.update()
+
+      expect(height()).toBe(60)
+    })
   })
 
   describe('dispose', () => {