diff --git a/crates/zensical/src/compat/mkdocs/plugin/minify/html.rs b/crates/zensical/src/compat/mkdocs/plugin/minify/html.rs
index 6417914..65dd635 100644
--- a/crates/zensical/src/compat/mkdocs/plugin/minify/html.rs
+++ b/crates/zensical/src/compat/mkdocs/plugin/minify/html.rs
@@ -177,6 +177,60 @@ mod tests {
         assert_eq!(output, r#"<input disabled title="a&amp;b" alt>"#);
     }
 
+    #[test]
+    fn preserves_utf8_attribute_values() {
+        // Two-, three-, and four-byte characters are retained in quoted and
+        // unquoted values, including the mismatched quotes from issue #1013.
+        let cases = [
+            (
+                r#"<div class=“foo">x</div>"#,
+                r#"<div class='“foo"'>x</div>"#,
+            ),
+            ("<div title=é>x</div>", "<div title=é>x</div>"),
+            ("<div title=中文>x</div>", "<div title=中文>x</div>"),
+            ("<div title=😀>x</div>", "<div title=😀>x</div>"),
+            ("<div title=a“b>x</div>", "<div title=a“b>x</div>"),
+            ("<div title=foo“>x</div>", "<div title=foo“>x</div>"),
+            (r#"<div title="“foo">x</div>"#, "<div title=“foo>x</div>"),
+            ("<div title='😀'>x</div>", "<div title=😀>x</div>"),
+        ];
+
+        for convert_charrefs in [true, false] {
+            let mut options = options();
+            options.convert_charrefs = convert_charrefs;
+
+            for (input, expected) in cases {
+                let output = minify(input, &options, false, false);
+
+                assert_eq!(output, expected, "input: {input}");
+            }
+        }
+    }
+
+    #[test]
+    fn preserves_unquoted_attribute_source_spelling() {
+        // Source spelling is retained when character-reference conversion is
+        // disabled or an attribute is protected with the configured prefix.
+        let mut options = options();
+        options.convert_charrefs = false;
+        let input =
+            "<div class=foo id=x title=&quot;é&amp;😀 data-value=é>x</div>";
+
+        let output = minify(input, &options, false, false);
+
+        assert_eq!(output, input);
+
+        options.convert_charrefs = true;
+        let input = "<div pre-class=foo pre-id=x pre-title=&quot;é&amp;😀 pre-data-value=é>x</div>";
+
+        let output = minify(input, &options, false, false);
+
+        assert_eq!(
+            output,
+            "<div class=foo id=x title=&quot;é&amp;😀 data-value=é>x</div>"
+        );
+    }
+
     #[test]
     fn supports_custom_preservation_markers() {
         let mut options = options();
@@ -293,6 +347,28 @@ mod tests {
         assert!(output.ends_with("<script>const x=1;</script>"));
     }
 
+    #[test]
+    fn inline_only_retains_utf8_attribute_values() {
+        // Surrounding HTML is preserved while inline languages are minified,
+        // even when an unquoted attribute starts with a multi-byte character.
+        let input = concat!(
+            r#"<div class=“foo" title=é data-value=😀>x</div>"#,
+            "<script data-value=中文> const x = 1; </script>",
+            "<style data-value=😀> .a { color: red; } </style>",
+        );
+
+        let output = minify_inline(input.into(), true, true);
+
+        assert_eq!(
+            output,
+            concat!(
+                r#"<div class=“foo" title=é data-value=😀>x</div>"#,
+                "<script data-value=中文>const x=1;</script>",
+                "<style data-value=😀>.a{color:red}</style>",
+            )
+        );
+    }
+
     #[test]
     fn inline_minification_never_expands_a_body() {
         let input = "<script>x()</script><style>a{color:red}</style>";
diff --git a/crates/zensical/src/compat/mkdocs/plugin/minify/html/inline.rs b/crates/zensical/src/compat/mkdocs/plugin/minify/html/inline.rs
index 647b043..528b355 100644
--- a/crates/zensical/src/compat/mkdocs/plugin/minify/html/inline.rs
+++ b/crates/zensical/src/compat/mkdocs/plugin/minify/html/inline.rs
@@ -32,8 +32,8 @@ use std::ops::Range;
 use crate::compat::mkdocs::plugin::minify::{script, style};
 
 use super::syntax::{
-    is_css, is_javascript, is_module, source_name, Attribute, InlineKind,
-    StartTag, Value,
+    is_css, is_javascript, is_module, source_name, source_value, Attribute,
+    InlineKind, StartTag, Value,
 };
 
 // ----------------------------------------------------------------------------
@@ -120,7 +120,7 @@ impl<'a> InlineEditor<'a> {
         {
             attribute.value = Some(Value {
                 decoded: String::from_utf8_lossy(value).into_owned(),
-                raw: self.input[span.start..span.end].into(),
+                raw: source_value(self.input, span),
             });
         }
     }
diff --git a/crates/zensical/src/compat/mkdocs/plugin/minify/html/serializer.rs b/crates/zensical/src/compat/mkdocs/plugin/minify/html/serializer.rs
index 36d3463..1832305 100644
--- a/crates/zensical/src/compat/mkdocs/plugin/minify/html/serializer.rs
+++ b/crates/zensical/src/compat/mkdocs/plugin/minify/html/serializer.rs
@@ -34,8 +34,8 @@ use crate::config::plugins::HtmlMinOptions;
 use super::syntax::{
     closes_on_start, collapse_whitespace, escape_text, is_boolean_attribute,
     is_css, is_html_whitespace, is_javascript, is_module, is_void,
-    serialize_attribute_value, source_name, Attribute, Element, Inline,
-    InlineKind, StartTag, Value,
+    serialize_attribute_value, source_name, source_value, Attribute, Element,
+    Inline, InlineKind, StartTag, Value,
 };
 
 // ----------------------------------------------------------------------------
@@ -151,7 +151,7 @@ impl<'a> Serializer<'a> {
         };
         attribute.value = Some(Value {
             decoded: String::from_utf8_lossy(value).into_owned(),
-            raw: self.input[span.start..span.end].into(),
+            raw: source_value(self.input, span),
         });
     }
 
diff --git a/crates/zensical/src/compat/mkdocs/plugin/minify/html/syntax.rs b/crates/zensical/src/compat/mkdocs/plugin/minify/html/syntax.rs
index 7a04eed..50c30d8 100644
--- a/crates/zensical/src/compat/mkdocs/plugin/minify/html/syntax.rs
+++ b/crates/zensical/src/compat/mkdocs/plugin/minify/html/syntax.rs
@@ -131,6 +131,18 @@ pub fn source_name(
     input.get(start..end).unwrap_or_default().into()
 }
 
+/// An attribute value is extracted with its source spelling.
+pub fn source_value(input: &str, span: Span<usize>) -> String {
+    // The opening quote or first unquoted byte is excluded from html5gum's
+    // attribute-value spans. The first byte must be restored for unquoted
+    // values.
+    let mut start = span.start - 1;
+    if matches!(input.as_bytes()[start], b'\'' | b'"') {
+        start += 1;
+    }
+    input[start..span.end].into()
+}
+
 /// Returns whether a character is HTML whitespace.
 pub fn is_html_whitespace(character: char) -> bool {
     matches!(character, '\t' | '\n' | '\u{c}' | '\r' | ' ')
diff --git a/python/tests/integration/test_minify.py b/python/tests/integration/test_minify.py
index f1b0e45..5972ccf 100644
--- a/python/tests/integration/test_minify.py
+++ b/python/tests/integration/test_minify.py
@@ -117,6 +117,31 @@ def test_inline_minification_does_not_require_html_minification(
     assert "screen and (min-width:45em)" in output
 
 
+@pytest.mark.parametrize(
+    ("minify_html", "expected"),
+    [
+        (True, """<div class='“foo"'>x</div>"""),
+        (False, '<div class=“foo">x</div>'),
+    ],
+)
+def test_minification_preserves_utf8_attribute_values(
+    tmp_path: Path,
+    minify_html: bool,
+    expected: str,
+) -> None:
+    """Preserve UTF-8 attribute values during HTML and inline minification."""
+    config = _project(tmp_path, minify_html=minify_html)
+
+    # The mismatched quotes from issue #1013 are included in the rendered page.
+    with (tmp_path / "docs" / "index.md").open("a", encoding="utf-8") as stream:
+        stream.write('\n<div class=“foo">x</div>\n')
+
+    zensical.build(str(config), {"clean": False, "strict": False})
+    output = (tmp_path / "site" / "index.html").read_text(encoding="utf-8")
+
+    assert expected in output
+
+
 def _asset_project(root: Path, *, minify: bool, cache_safe: bool) -> Path:
     """Create a project covering exact, glob, and configured assets."""
     docs = root / "docs"