diff --git a/.changeset/fuzzy-dodos-prune.md b/.changeset/fuzzy-dodos-prune.md
new file mode 100644
index 00000000..0cd376b0
--- /dev/null
+++ b/.changeset/fuzzy-dodos-prune.md
@@ -0,0 +1,5 @@
+---
+"leadtype": patch
+---
+
+Fix `convertAllMdx()` directory pruning on Windows by normalizing globbed paths before comparing them with the output directory.
diff --git a/packages/leadtype/src/convert/convert.test.ts b/packages/leadtype/src/convert/convert.test.ts
index 76065a15..2a057989 100644
--- a/packages/leadtype/src/convert/convert.test.ts
+++ b/packages/leadtype/src/convert/convert.test.ts
@@ -22,6 +22,7 @@ import {
   convertAllMdx,
   convertMdxFile,
   resolveMdxFrontmatter,
+  resolvePruneParentDirectories,
 } from "./convert";
 
 const execFileAsync = promisify(execFile);
@@ -82,6 +83,18 @@ afterEach(async () => {
 });
 
 describe("convertAllMdx", () => {
+  it("normalizes glob paths before pruning directories on Windows", () => {
+    const parents = resolvePruneParentDirectories(
+      [
+        "C:/repo/public/guides/orphan.md",
+        "C:\\repo\\public\\guides\\another-orphan.md",
+      ],
+      path.win32
+    );
+
+    expect([...parents]).toEqual(["C:\\repo\\public\\guides"]);
+  });
+
   it("defaults to the framework-neutral docs directory", async () => {
     const projectDir = await createTempProject();
     const previousCwd = process.cwd();
diff --git a/packages/leadtype/src/convert/convert.ts b/packages/leadtype/src/convert/convert.ts
index ff33e4a4..7fb9078a 100644
--- a/packages/leadtype/src/convert/convert.ts
+++ b/packages/leadtype/src/convert/convert.ts
@@ -1272,7 +1272,7 @@ async function pruneOrphanedOutputs(
   // Deleting the last page of a section leaves an empty directory behind;
   // sweep upward until a non-empty parent (or outDir) stops the walk.
   const resolvedOutDir = resolve(outDir);
-  const parents = new Set(orphans.map((filePath) => dirname(filePath)));
+  const parents = resolvePruneParentDirectories(orphans);
   for (let dir of parents) {
     while (dir !== resolvedOutDir && dir.startsWith(resolvedOutDir + sep)) {
       try {
@@ -1287,6 +1287,21 @@ async function pruneOrphanedOutputs(
   return orphans;
 }
 
+interface PrunePathApi {
+  dirname: (filePath: string) => string;
+  resolve: (...paths: string[]) => string;
+}
+
+/** Normalize glob output before comparing it with native filesystem paths. */
+export function resolvePruneParentDirectories(
+  filePaths: readonly string[],
+  pathApi: PrunePathApi = { dirname, resolve }
+): Set<string> {
+  return new Set(
+    filePaths.map((filePath) => pathApi.resolve(pathApi.dirname(filePath)))
+  );
+}
+
 /**
  * Convert every .mdx file under srcDir to .md under outDir (preserving the
  * relative directory structure).