diff --git a/Libraries/LibWeb/CMakeLists.txt b/Libraries/LibWeb/CMakeLists.txt
index c2afad4e37c..565542c078b 100644
--- a/Libraries/LibWeb/CMakeLists.txt
+++ b/Libraries/LibWeb/CMakeLists.txt
@@ -999,7 +999,8 @@ if (ENABLE_SWIFT)
         HTML/Parser/HTMLToken.swift
         HTML/Parser/HTMLTokenizer.swift
         HTML/Parser/HTMLTokenizerHelpers.cpp
+        HTML/Parser/SpeculativeHTMLParser.swift
     )
     target_link_libraries(LibWeb PRIVATE AK Collections)
-    add_swift_target_properties(LibWeb LAGOM_LIBRARIES AK LibGfx)
+    add_swift_target_properties(LibWeb LAGOM_LIBRARIES AK LibGfx LibGC COMPILE_DEFINITIONS LIBGC_WORKAROUND_BOOL_BITFIELD)
 endif()
diff --git a/Libraries/LibWeb/HTML/Parser/HTMLParser.h b/Libraries/LibWeb/HTML/Parser/HTMLParser.h
index 45b53fc99a0..16902a40c76 100644
--- a/Libraries/LibWeb/HTML/Parser/HTMLParser.h
+++ b/Libraries/LibWeb/HTML/Parser/HTMLParser.h
@@ -214,10 +214,14 @@ private:
 
     GC::Ptr<DOM::Text> m_character_insertion_node;
     StringBuilder m_character_insertion_builder;
-};
+} SWIFT_UNSAFE_REFERENCE;
 
 RefPtr<CSS::CSSStyleValue> parse_dimension_value(StringView);
 RefPtr<CSS::CSSStyleValue> parse_nonzero_dimension_value(StringView);
 Optional<Color> parse_legacy_color_value(StringView);
 
+// Swift interop
+using HTMLParserGCPtr = GC::Ptr<HTMLParser>;
+using HTMLParserGCRef = GC::Ref<HTMLParser>;
+
 }
diff --git a/Libraries/LibWeb/HTML/Parser/SpeculativeHTMLParser.swift b/Libraries/LibWeb/HTML/Parser/SpeculativeHTMLParser.swift
new file mode 100644
index 00000000000..fae5d34d124
--- /dev/null
+++ b/Libraries/LibWeb/HTML/Parser/SpeculativeHTMLParser.swift
@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2025, Andrew Kaster <andrew@ladybird.org>>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+import AK
+import Collections
+import Foundation
+import GC
+@_exported import WebCxx
+
+// Workaround for https://github.com/swiftlang/swift/issues/80231
+// If any line of this changes, the whole thing breaks though
+extension GC.Cell.Visitor {
+    public func visit(_ parser: Web.HTML.HTMLParserGCPtr) {
+        if let parser = parser.ptr() {
+            let cell: GC.Cell = cxxCast(parser)
+            visit(cell)
+        }
+    }
+}
+
+struct SpeculativeMockElement {
+    let name: Swift.String
+    let localName: Swift.String
+    let attributes: [HTMLToken.Attribute]
+    var children: [SpeculativeMockElement]
+
+    init(name: Swift.String, localName: Swift.String, attributes: [HTMLToken.Attribute]) {
+        self.name = name
+        self.localName = localName
+        self.attributes = attributes
+        self.children = []
+    }
+
+    mutating func appendChild(_ child: consuming SpeculativeMockElement) {
+        children.append(child)
+    }
+}
+
+public final class SpeculativeHTMLParser: HeapAllocatable {
+    var parser = Web.HTML.HTMLParserGCPtr()  // FIXME: Want HTMLParserGCRef here, but how to initialize it?
+
+    public init(cell: GC.Cell) {
+        self.cell = cell
+    }
+    public var cell: GC.Cell
+
+    public static func create(on heap: GC.Heap, `for` parser: Web.HTML.HTMLParserGCPtr) -> GC.Cell {
+        precondition(heap.is_gc_deferred())
+        let _self = allocate(on: heap)
+        _self.pointee.parser = parser
+        return _self.pointee.cell
+    }
+
+    public func visitEdges(_ visitor: GC.Cell.Visitor) {
+        visitor.visit(parser)
+    }
+}
diff --git a/Libraries/LibWeb/Loader/FileRequest.h b/Libraries/LibWeb/Loader/FileRequest.h
index 05f862dafb7..8e7828915e6 100644
--- a/Libraries/LibWeb/Loader/FileRequest.h
+++ b/Libraries/LibWeb/Loader/FileRequest.h
@@ -9,6 +9,7 @@
 #include <AK/ByteString.h>
 #include <AK/Error.h>
 #include <AK/Function.h>
+#include <AK/Swift.h>
 
 namespace Web {
 
@@ -22,6 +23,6 @@ public:
 
 private:
     ByteString m_path {};
-};
+} SWIFT_UNSAFE_REFERENCE; // FIXME: This type is actually move-only, not unsafe
 
 }
diff --git a/Tests/LibWeb/CMakeLists.txt b/Tests/LibWeb/CMakeLists.txt
index bd34970a44f..fa0c06e3782 100644
--- a/Tests/LibWeb/CMakeLists.txt
+++ b/Tests/LibWeb/CMakeLists.txt
@@ -29,6 +29,6 @@ if (ENABLE_SWIFT)
     target_sources(TestLibWebSwift PRIVATE ../Resources/SwiftTestMain.swift)
 
     set_target_properties(TestLibWebSwift PROPERTIES SUFFIX .swift-testing)
-    target_link_libraries(TestLibWebSwift PRIVATE AK LibWeb SwiftTesting::SwiftTesting)
+    target_link_libraries(TestLibWebSwift PRIVATE AK LibWeb LibGC SwiftTesting::SwiftTesting)
     add_test(NAME TestLibWebSwift COMMAND TestLibWebSwift)
 endif()