diff --git a/packages/block-editor/src/components/rich-text/use-paste-handler.js b/packages/block-editor/src/components/rich-text/use-paste-handler.js
index 561efc9359ed3..5d2d4968f681a 100644
--- a/packages/block-editor/src/components/rich-text/use-paste-handler.js
+++ b/packages/block-editor/src/components/rich-text/use-paste-handler.js
@@ -261,6 +261,9 @@ export function usePasteHandler( props ) {
  * @return {string} the normalized html
  */
 function removeWindowsFragments( html ) {
+	if ( ! html.includes( '<!--StartFragment-->' ) ) {
+		return html;
+	}
 	const startReg = /.*<!--StartFragment-->/s;
 	const endReg = /<!--EndFragment-->.*/s;