diff --git a/README.md b/README.md
index 3cfc0b1..d278938 100644
--- a/README.md
+++ b/README.md
@@ -77,8 +77,8 @@ echo '# Hello' | md2mdhtml
 md2mdhtml input.md > out.html
 md2mdhtml --math=on input.md > out.html
 md2mdhtml --math=dollars input.md > out.html
-md2mdhtml --implicit_figures input.md > out.html
-md2mdhtml --no-bare_autolinks input.md > out.html
+md2mdhtml --implicit-figures input.md > out.html
+md2mdhtml --no-bare-autolinks input.md > out.html
 ```
 
 `md2html` goes the rest of the way, lowering that fragment to a finished HTML page: references baked, headings and captions numbered, code highlighted (```` ```markdown ```` fences by mdhtml itself, everything else by the optional fastpylight extra), mustache tokens shown as styled pills, and the assets those features need (`dialect_css`, light and dark fastpylight themes, KaTeX plus `math_js`) composed into the page. With no `--out` it writes the page under `~/.cache/md2html/` and opens it in a browser, inlining local images so the page renders from anywhere; piped, it writes to stdout instead, and `--out -` forces that even at a terminal. `--fragment` emits the body alone. `--frontmatter` recognizes a leading metadata block (see below), and ```mermaid fences become diagrams drawn in place by mermaid.js. References default to `--refs=ids`, which shows each reference's target id and never fails on a draft; `--refs=resolve` numbers them and raises on a broken one, and `--refs=lenient` numbers what it can and warns about the rest.
@@ -87,7 +87,7 @@ md2mdhtml --no-bare_autolinks input.md > out.html
 md2html input.md
 md2html examples/sample.md
 md2html --refs=lenient draft.md
-md2html --number_headings=legal --toc input.md --out out.html
+md2html --number-headings=legal --toc input.md --out out.html
 md2html --theme=onedark --hl=api input.md --out -
 ```
 
diff --git a/tests/test_python.py b/tests/test_python.py
index 137c96c..6151a84 100644
--- a/tests/test_python.py
+++ b/tests/test_python.py
@@ -762,7 +762,7 @@ def test_cli_reads_markdown_from_stdin():
     assert_html(res.stdout, "<h1>Hello</h1>")
     assert res.stderr == ""
 
-    res = subprocess.run(["md2mdhtml", "--implicit_figures"],
+    res = subprocess.run(["md2mdhtml", "--implicit-figures"],
         input="# Hello\n\n![A picture](pic.png)\n", text=True, capture_output=True, check=True)
     assert_html(res.stdout, '<h1>Hello</h1><figure><img src="pic.png" alt=""><figcaption>A picture</figcaption></figure>')
 
@@ -774,7 +774,7 @@ def test_cli_defaults_to_bracket_math():
 
 
 def test_cli_can_disable_bare_autolinks():
-    res = subprocess.run(["md2mdhtml", "--no-bare_autolinks"], input="https://example.com\n",
+    res = subprocess.run(["md2mdhtml", "--no-bare-autolinks"], input="https://example.com\n",
         text=True, capture_output=True, check=True)
     assert_html(res.stdout, "<p>https://example.com</p>")