diff --git a/docs/resources/changelog.md b/docs/resources/changelog.md
index f07815ee..d4fb4527 100644
--- a/docs/resources/changelog.md
+++ b/docs/resources/changelog.md
@@ -13,13 +13,14 @@ _During the beta period, these restrictions may be relaxed in the event of a mis
 - Added `--spacing` CSS custom property to `<sl-divider>` [#664](https://github.com/shoelace-style/shoelace/pull/664)
 - Fixed a bug that caused `<sl-progress-ring>` to render the wrong size when `--track-width` was increased [#656](https://github.com/shoelace-style/shoelace/issues/656)
 - Fixed a bug that allowed `<sl-details>` to open and close when disabled using a screen reader [#658](https://github.com/shoelace-style/shoelace/issues/658)
+- Fixed a bug in the FormData event polyfill that threw an error in some environments [#666](https://github.com/shoelace-style/shoelace/issues/666)
 - Implemented stricter linting to improve consistency and reduce errors, which resulted in many small refactors throughout the codebase [#647](https://github.com/shoelace-style/shoelace/pull/647)
 - Improved accessibility of `<sl-dialog>` and `<sl-drawer>` by making the title an `<h2>` and adding a label to the close button
 - Improved search results in the documentation
 - Refactored `<sl-format-byte>` to use `Intl.NumberFormat` so it supports localization
 - Refactored themes so utility styles are no longer injected as `<style>` elements to support stricter CSP rules [#571](https://github.com/shoelace-style/shoelace/issues/571)
 - Restored the nicer animation on `<sl-spinner>` and verified it works in Safari
-- Updated Feature icon example to use Lucide
+- Updated Feather icon example to use Lucide  [#657](https://github.com/shoelace-style/shoelace/issues/657)
 - Updated minimum Node version to 14.17
 - Updated Lit to 2.1.2
 - Updated to Bootstrap Icons to 1.8.0
diff --git a/src/internal/formdata-event-polyfill.ts b/src/internal/formdata-event-polyfill.ts
index 114d5fc2..4f7cb205 100644
--- a/src/internal/formdata-event-polyfill.ts
+++ b/src/internal/formdata-event-polyfill.ts
@@ -91,4 +91,8 @@ function polyfillFormData() {
   });
 }
 
-polyfillFormData();
+if (document.readyState === 'complete') {
+  polyfillFormData();
+} else {
+  window.addEventListener('DOMContentLoaded', () => polyfillFormData());
+}