diff --git a/toolkit/locales/en-US/chrome/mozapps/downloads/unknownContentType.properties b/toolkit/locales/en-US/chrome/mozapps/downloads/unknownContentType.properties
index fa3c5e389bad5abb05c86a3cb08d6c7abf34166c..1bb1f48c4d3964e4637462bb0b3d4a1e965ca5ec 100644
--- a/toolkit/locales/en-US/chrome/mozapps/downloads/unknownContentType.properties
+++ b/toolkit/locales/en-US/chrome/mozapps/downloads/unknownContentType.properties
@@ -17,6 +17,7 @@ fileType=%S file
 # LOCALIZATION NOTE (orderedFileSizeWithType): first %S is type, second %S is size, and third %S is unit
 orderedFileSizeWithType=%1$S (%2$S %3$S)
 avifExtHandlerDescription=AV1 Image File (AVIF)
+jxlExtHandlerDescription=JPEG XL Image (JXL)
 pdfExtHandlerDescription=Portable Document Format (PDF)
 svgExtHandlerDescription=Scalable Vector Graphics (SVG)
 webpExtHandlerDescription=WebP Image
