diff --git a/.sampo/changesets/stern-bard-goulven.md b/.sampo/changesets/stern-bard-goulven.md
new file mode 100644
index 00000000..1b3728ad
--- /dev/null
+++ b/.sampo/changesets/stern-bard-goulven.md
@@ -0,0 +1,5 @@
+---
+npm/satteri: patch
+---
+
+Aligns directive attribute type with `mdast-util-directive` by allowing nullish attribute values.
diff --git a/packages/satteri/src/directive-types.ts b/packages/satteri/src/directive-types.ts
index 922d6aa5..c0dd24d2 100644
--- a/packages/satteri/src/directive-types.ts
+++ b/packages/satteri/src/directive-types.ts
@@ -13,7 +13,11 @@ import type {
   PhrasingContent,
 } from "mdast";
 
-export type DirectiveAttributes = Record<string, string>;
+// Even though `null` and `undefined` values are omitted in both Sätteri and mdast-util-directive,
+// they're allowed in the type definitions here to match the mdast-util-directive type.
+// https://github.com/syntax-tree/mdast-util-directive/blob/a683327fafc4e48f81caf8d09d15fef8dd42a627/lib/index.js#L212-L213
+// https://github.com/syntax-tree/mdast-util-directive/blob/main/index.d.ts#L49
+export type DirectiveAttributes = Record<string, string | null | undefined>;
 
 export interface ContainerDirective extends MdastParent {
   type: "containerDirective";
diff --git a/packages/satteri/test/visitor.test.ts b/packages/satteri/test/visitor.test.ts
index 03526d63..51540cbb 100644
--- a/packages/satteri/test/visitor.test.ts
+++ b/packages/satteri/test/visitor.test.ts
@@ -12,7 +12,7 @@ import {
   applyCommandsAndConvertToHastHandle,
   renderHandle,
 } from "../index.js";
-import type { MdastNode } from "../src/types.js";
+import type { DirectiveAttributes, MdastNode } from "../src/types.js";
 import type { Heading, Text } from "mdast";
 import { defineMdastPlugin } from "../src/plugin.js";
 import { markdownToHtml, applyCommandsToMdastHandle } from "../src/index.js";
@@ -488,7 +488,7 @@ function setupDirective(md: string) {
 
 test("containerDirective visitor fires and exposes name + attributes", () => {
   const { handle, source } = setupDirective(":::tip{.note #id}\nbody\n:::\n");
-  const seen: { name: string; attributes: Record<string, string> }[] = [];
+  const seen: { name: string; attributes: DirectiveAttributes }[] = [];
   const plugin = defineMdastPlugin({
     name: "collect-container-directive",
     containerDirective(node) {
@@ -521,7 +521,7 @@ test("containerDirective with [label] exposes directiveLabel marker on first chi
 
 test("leafDirective visitor fires and exposes name", () => {
   const { handle, source } = setupDirective("::break{aria-label=section}\n");
-  const seen: { name: string; attributes: Record<string, string> }[] = [];
+  const seen: { name: string; attributes: DirectiveAttributes }[] = [];
   const plugin = defineMdastPlugin({
     name: "collect-leaf-directive",
     leafDirective(node) {