diff --git a/web/src/utils/markdown-manipulation.ts b/web/src/utils/markdown-manipulation.ts
index a85a7d46..f1461547 100644
--- a/web/src/utils/markdown-manipulation.ts
+++ b/web/src/utils/markdown-manipulation.ts
@@ -137,11 +137,13 @@ export function extractHeadings(markdown: string): HeadingItem[] {
 }
 
 interface MdastNode {
+  type?: string;
   value?: string;
   children?: MdastNode[];
 }
 
 function getNodeText(node: MdastNode): string {
+  if (node.type === "html") return "";
   if (node.value) return node.value;
   if (node.children) return node.children.map(getNodeText).join("");
   return "";
diff --git a/web/tests/markdown-manipulation.test.ts b/web/tests/markdown-manipulation.test.ts
new file mode 100644
index 00000000..beaaa273
--- /dev/null
+++ b/web/tests/markdown-manipulation.test.ts
@@ -0,0 +1,16 @@
+import { describe, expect, it } from "vitest";
+import { extractHeadings } from "@/utils/markdown-manipulation";
+
+describe("extractHeadings", () => {
+  it("uses rendered text for headings containing inline HTML", () => {
+    const headings = extractHeadings(`# <ruby>連濁<rt>れんだく</rt></ruby>: "Why Hito-Bito isn't Hito-Hito"`);
+
+    expect(headings).toEqual([
+      {
+        text: `連濁れんだく: "Why Hito-Bito isn't Hito-Hito"`,
+        level: 1,
+        slug: "why-hito-bito-isnt-hito-hito",
+      },
+    ]);
+  });
+});