diff --git a/src/chooser.ts b/src/chooser.ts
index de65aaf..9b5a92f 100644
--- a/src/chooser.ts
+++ b/src/chooser.ts
@@ -295,7 +295,7 @@ export class Chooser extends LitElement {
                   type="text"
                   name="filename"
                   id="filename"
-                  pattern="((file|http|https|ipfs|s3)://.*.(warc|warc.gz|zip|wacz|har|json)([?#].*)?)|(googledrive://.+)|(ssb://.+)"
+                  pattern="((file|http|https|ipfs|s3)://.*.(warc|warc.gz|zip|wacz|har|json|cdx)([?#].*)?)|(googledrive://.+)|(ssb://.+)"
                   .value="${this.fileDisplayName}"
                   @input="${this.onInput}"
                   autocomplete="off"