diff --git a/Libraries/LibWeb/CSS/CSSFontFaceRule.cpp b/Libraries/LibWeb/CSS/CSSFontFaceRule.cpp
index 5f758712324..aa41229d260 100644
--- a/Libraries/LibWeb/CSS/CSSFontFaceRule.cpp
+++ b/Libraries/LibWeb/CSS/CSSFontFaceRule.cpp
@@ -65,11 +65,15 @@ String CSSFontFaceRule::serialized() const
 
         // 2. The result of invoking serialize a comma-separated list on performing serialize a URL or serialize a LOCAL for each source on the source list.
         serialize_a_comma_separated_list(builder, m_font_face.sources(), [&](StringBuilder& builder, ParsedFontFace::Source source) -> void {
-            if (source.local_or_url.has<URL::URL>()) {
-                serialize_a_url(builder, source.local_or_url.get<URL::URL>().to_string());
-            } else {
-                builder.appendff("local({})", source.local_or_url.get<FlyString>());
-            }
+            source.local_or_url.visit(
+                [&builder](URL::URL const& url) {
+                    serialize_a_url(builder, url.to_string());
+                },
+                [&builder](FlyString const& local) {
+                    // https://drafts.csswg.org/cssom-1/#serialize-a-local
+                    // To serialize a LOCAL means to create a string represented by "local(", followed by the serialization of the LOCAL as a string, followed by ")".
+                    builder.appendff("local({})", serialize_a_string(local));
+                });
 
             // NOTE: No spec currently exists for format()
             if (source.format.has_value()) {
diff --git a/Libraries/LibWeb/CSS/Parser/RuleParsing.cpp b/Libraries/LibWeb/CSS/Parser/RuleParsing.cpp
index aa3c39fa16e..153b5085ccc 100644
--- a/Libraries/LibWeb/CSS/Parser/RuleParsing.cpp
+++ b/Libraries/LibWeb/CSS/Parser/RuleParsing.cpp
@@ -28,6 +28,7 @@
 #include <LibWeb/CSS/Parser/Parser.h>
 #include <LibWeb/CSS/PropertyName.h>
 #include <LibWeb/CSS/StyleValues/CSSKeywordValue.h>
+#include <LibWeb/CSS/StyleValues/CustomIdentStyleValue.h>
 #include <LibWeb/CSS/StyleValues/IntegerStyleValue.h>
 #include <LibWeb/CSS/StyleValues/NumberStyleValue.h>
 #include <LibWeb/CSS/StyleValues/OpenTypeTaggedStyleValue.h>
@@ -669,10 +670,28 @@ Vector<ParsedFontFace::Source> Parser::parse_font_face_src(TokenStream<T>& compo
 
         auto const& first = source_tokens.consume_a_token();
         if (first.is_function("local"sv)) {
+            // local(<family-name>)
             if (first.function().value.is_empty()) {
-                continue;
+                dbgln_if(CSS_PARSER_DEBUG, "CSSParser: @font-face src invalid (`local()` syntax is invalid: no arguments); discarding.");
+                return {};
             }
-            supported_sources.empend(FlyString { first.function().value.first().to_string() }, Optional<FlyString> {});
+
+            TokenStream function_tokens { first.function().value };
+            function_tokens.discard_whitespace();
+            auto font_family = parse_family_name_value(function_tokens);
+            function_tokens.discard_whitespace();
+            if (!font_family || function_tokens.has_next_token()) {
+                dbgln_if(CSS_PARSER_DEBUG, "CSSParser: @font-face src invalid (`local()` syntax is invalid: `{}`); discarding.", first.function().original_source_text());
+                return {};
+            }
+
+            if (font_family->is_string())
+                supported_sources.empend(font_family->as_string().string_value(), Optional<FlyString> {});
+            else if (font_family->is_custom_ident())
+                supported_sources.empend(font_family->as_custom_ident().custom_ident(), Optional<FlyString> {});
+            else
+                VERIFY_NOT_REACHED();
+
             continue;
         }