2 files changed, 60 insertions, 9 deletions
diff --git a/src/construct/frontmatter.rs b/src/construct/frontmatter.rs
index 268d91d..f4774d6 100644
--- a/src/construct/frontmatter.rs
+++ b/src/construct/frontmatter.rs
@@ -281,13 +281,10 @@ pub fn content_end(tokenizer: &mut Tokenizer) -> State {
 ///        ^
 /// ```
 pub fn after(tokenizer: &mut Tokenizer) -> State {
-    tokenizer.tokenize_state.marker = 0;
-
-    match tokenizer.current {
-        None | Some(b'\n') => {
-            tokenizer.exit(Name::Frontmatter);
-            State::Ok
-        }
-        _ => State::Nok,
-    }
+    debug_assert!(
+        matches!(tokenizer.current, None | Some(b'\n')),
+        "expected eol/eof after closing fence"
+    );
+    tokenizer.exit(Name::Frontmatter);
+    State::Ok
 }
diff --git a/tests/frontmatter.rs b/tests/frontmatter.rs
index 267b694..b1380b6 100644
--- a/tests/frontmatter.rs
+++ b/tests/frontmatter.rs
@@ -45,12 +45,60 @@ fn frontmatter() -> Result<(), String> {
     );
 
     assert_eq!(
+        to_html_with_options("--\n---", &frontmatter)?,
+        "<h2>--</h2>",
+        "should not support 2 markers in an opening fence"
+    );
+
+    assert_eq!(
+        to_html_with_options("----\n---", &frontmatter)?,
+        "<hr />\n<hr />",
+        "should not support 4 markers in an opening fence"
+    );
+
+    assert_eq!(
+        to_html_with_options("---\n--", &frontmatter)?,
+        "<hr />\n<p>--</p>",
+        "should not support 2 markers in a closing fence"
+    );
+
+    assert_eq!(
+        to_html_with_options("---\n----", &frontmatter)?,
+        "<hr />\n<hr />",
+        "should not support 4 markers in a closing fence"
+    );
+
+    assert_eq!(
         to_html_with_options("---\n---\n## Neptune", &frontmatter)?,
         "<h2>Neptune</h2>",
         "should support content after frontmatter"
     );
 
     assert_eq!(
+        to_html_with_options("--- \t\n---", &frontmatter)?,
+        "",
+        "should support spaces and tabs after opening fence"
+    );
+
+    assert_eq!(
+        to_html_with_options("---\n---\t ", &frontmatter)?,
+        "",
+        "should support spaces and tabs after closing fence"
+    );
+
+    assert_eq!(
+        to_html_with_options("--- a\n---", &frontmatter)?,
+        "<h2>--- a</h2>",
+        "should not support content after opening fence"
+    );
+
+    assert_eq!(
+        to_html_with_options("---\n--- b", &frontmatter)?,
+        "<hr />\n<p>--- b</p>",
+        "should not support content after closing fence"
+    );
+
+    assert_eq!(
         to_html_with_options("## Neptune\n---\n---", &frontmatter)?,
         "<h2>Neptune</h2>\n<hr />\n<hr />",
         "should not support frontmatter after content"
@@ -75,6 +123,12 @@ fn frontmatter() -> Result<(), String> {
     );
 
     assert_eq!(
+        to_html_with_options("---\na\n\nb\n \t\nc\n---", &frontmatter)?,
+        "",
+        "should support blank lines in frontmatter"
+    );
+
+    assert_eq!(
         to_mdast("---\na: b\n---", &frontmatter.parse)?,
         Node::Root(Root {
             children: vec![Node::Yaml(Yaml {