diff --git a/pdf2md.py b/pdf2md.py
index 0ac317c..cc7cdc1 100644
--- a/pdf2md.py
+++ b/pdf2md.py
@@ -2120,6 +2120,7 @@ def write_epub(
         str(markdown_path),
         "--from", "markdown-yaml_metadata_block+autolink_bare_uris",
         "--to", "epub3",
+        "--mathml",   # $$...$$ (e.g. from formula_img2latex) as MathML, not as TeX text
         "--output", str(epub_path),
         "--resource-path", str(markdown_path.parent),
         f"--split-level={split_level}",