diff --git a/packages/url/src/index.js b/packages/url/src/index.js
index b4fa34efac51a6..2b549d6ba1dc4e 100644
--- a/packages/url/src/index.js
+++ b/packages/url/src/index.js
@@ -360,6 +360,10 @@ export function removeQueryArgs( url, ...args ) {
  * @return {string} The updated URL.
  */
 export function prependHTTP( url ) {
+	if ( ! url ) {
+		return url;
+	}
+
 	url = url.trim();
 	if ( ! USABLE_HREF_REGEXP.test( url ) && ! EMAIL_REGEXP.test( url ) ) {
 		return 'http://' + url;