diff --git a/tests/Memoizer.test.tsx b/tests/Memoizer.test.tsx
index f34696681e9f4e1329d2a4240ffa9d63bf2bd721..dfff941c57acf292713740f2422f685af67569cb 100644
--- a/tests/Memoizer.test.tsx
+++ b/tests/Memoizer.test.tsx
@@ -17,6 +17,30 @@ import {
 } from "../src/Memoizer.ts";
 
 const gfmProcessor = unified().use(remarkParse).use(remarkGfm);
+const documentStateProcessor = unified()
+  .use(remarkParse)
+  .use(function documentStatePlugin() {
+    return (tree: Parent) => {
+      const paragraphs = tree.children.filter(
+        (node): node is Parent =>
+          node.type === "paragraph" && "children" in node && Array.isArray(node.children),
+      );
+      const suffix = paragraphs
+        .map((paragraph) => paragraphText(paragraph))
+        .findLast((text) => text.startsWith("suffix: "))
+        ?.slice("suffix: ".length);
+      if (!suffix) return tree;
+
+      const target = paragraphs.find((paragraph) => !paragraphText(paragraph).startsWith("suffix: "));
+      const firstChild = target?.children[0];
+      if (firstChild?.type === "text") {
+        const textNode = firstChild as Literal;
+        const value = String(textNode.value);
+        textNode.value = `${value} (${suffix})`;
+      }
+      return tree;
+    };
+  });
 
 describe("Memoizer utilities", () => {
   it("finds the first differing index for edits in the middle, start, and end", () => {
@@ -143,8 +167,8 @@ describe("Memoizer incremental rendering", () => {
   it("keeps earlier gfm footnotes rendered when a later footnote definition is removed", () => {
     const incremental = createMemoizer(gfmProcessor);
 
-    incremental.update("a[^b]\n\n[^b]: bee\n\nc");
-    incremental.update("a[^b]\n\n[^b]: bee\n\nc[^d]\n\n[^d]: dee");
+    void incremental.update("a[^b]\n\n[^b]: bee\n\nc");
+    void incremental.update("a[^b]\n\n[^b]: bee\n\nc[^d]\n\n[^d]: dee");
     const after = renderNodes(incremental.update("a[^b]\n\n[^b]: bee\n\nc[^d]"));
 
     const fresh = createMemoizer(gfmProcessor);
@@ -222,6 +246,20 @@ describe("Memoizer incremental rendering", () => {
 
     expect(second[2]).toBe(first[2]);
   });
+
+  // TODO: this is a tough problem to cleanly solve without giving up too much memoization.
+  it.fails("re-renders earlier blocks when a later custom-plugin block changes document-wide state", () => {
+    const incremental = createMemoizer(documentStateProcessor);
+    void incremental.update("hello\n\nsuffix: one");
+
+    const after = renderNodes(incremental.update("hello\n\nsuffix: two"));
+
+    const fresh = createMemoizer(documentStateProcessor);
+    const expected = renderNodes(fresh.update("hello\n\nsuffix: two"));
+
+    expect(after).toBe(expected);
+    expect(expected).toContain("hello (two)");
+  });
 });
 
 function createMemoizer(processor = defaultProcessor, predict = false) {
@@ -233,3 +271,10 @@ function createMemoizer(processor = defaultProcessor, predict = false) {
 function renderNodes(nodes: readonly ReactNode[]) {
   return renderToStaticMarkup(<Fragment>{nodes}</Fragment>);
 }
+
+function paragraphText(node: Parent) {
+  return node.children
+    .filter((child): child is Literal => child.type === "text")
+    .map((child) => String(child.value))
+    .join("");
+}