diff --git a/apply.js b/apply.js
index d0302891..73a4e3a9 100644
--- a/apply.js
+++ b/apply.js
@@ -246,6 +246,8 @@ function applySections(styleId, sections) {
   if (document.documentElement instanceof SVGSVGElement) {
     // SVG document, make an SVG style element.
     el = document.createElementNS('http://www.w3.org/2000/svg', 'style');
+  } else if (document instanceof XMLDocument) {
+    el = document.createElementNS('http://www.w3.org/1999/xhtml', 'style');
   } else {
     // This will make an HTML style element. If there's SVG embedded in an HTML document, this works on the SVG too.
     el = document.createElement('style');