diff --git a/dev/lib/directive-container.js b/dev/lib/directive-container.js
index 08fc838..ea58083 100644
--- a/dev/lib/directive-container.js
+++ b/dev/lib/directive-container.js
@@ -5,7 +5,7 @@
  * @typedef {import('micromark-util-types').Token} Token
  */
 
-import assert from 'assert'
+import assert from 'power-assert'
 import {factorySpace} from 'micromark-factory-space'
 import {markdownLineEnding} from 'micromark-util-character'
 import {codes} from 'micromark-util-symbol/codes.js'
diff --git a/dev/lib/directive-leaf.js b/dev/lib/directive-leaf.js
index 283560c..f6c520b 100644
--- a/dev/lib/directive-leaf.js
+++ b/dev/lib/directive-leaf.js
@@ -4,7 +4,7 @@
  * @typedef {import('micromark-util-types').State} State
  */
 
-import assert from 'assert'
+import assert from 'power-assert'
 import {factorySpace} from 'micromark-factory-space'
 import {markdownLineEnding} from 'micromark-util-character'
 import {codes} from 'micromark-util-symbol/codes.js'
diff --git a/dev/lib/directive-text.js b/dev/lib/directive-text.js
index 67973ac..b37be0e 100644
--- a/dev/lib/directive-text.js
+++ b/dev/lib/directive-text.js
@@ -5,7 +5,7 @@
  * @typedef {import('micromark-util-types').State} State
  */
 
-import assert from 'assert'
+import assert from 'power-assert'
 import {codes} from 'micromark-util-symbol/codes.js'
 import {types} from 'micromark-util-symbol/types.js'
 import {factoryAttributes} from './factory-attributes.js'
diff --git a/dev/lib/factory-attributes.js b/dev/lib/factory-attributes.js
index 6c88a65..ac6a2ea 100644
--- a/dev/lib/factory-attributes.js
+++ b/dev/lib/factory-attributes.js
@@ -4,7 +4,7 @@
  * @typedef {import('micromark-util-types').Code} Code
  */
 
-import assert from 'assert'
+import assert from 'power-assert'
 import {factorySpace} from 'micromark-factory-space'
 import {factoryWhitespace} from 'micromark-factory-whitespace'
 import {
diff --git a/dev/lib/factory-label.js b/dev/lib/factory-label.js
index fa52028..ab8e7f4 100644
--- a/dev/lib/factory-label.js
+++ b/dev/lib/factory-label.js
@@ -3,7 +3,7 @@
  * @typedef {import('micromark-util-types').State} State
  */
 
-import assert from 'assert'
+import assert from 'power-assert'
 import {markdownLineEnding} from 'micromark-util-character'
 import {codes} from 'micromark-util-symbol/codes.js'
 import {constants} from 'micromark-util-symbol/constants.js'
diff --git a/dev/lib/html.js b/dev/lib/html.js
index 8955909..94cc7ce 100644
--- a/dev/lib/html.js
+++ b/dev/lib/html.js
@@ -21,7 +21,7 @@
  * @typedef {Record<string, Handle>} HtmlOptions
  */
 
-import assert from 'assert'
+import assert from 'power-assert'
 import {parseEntities} from 'parse-entities'
 
 const own = {}.hasOwnProperty
diff --git a/package.json b/package.json
index 42284c9..694a2d5 100644
--- a/package.json
+++ b/package.json
@@ -43,9 +43,11 @@
     "micromark-util-character": "^1.0.0",
     "micromark-util-symbol": "^1.0.0",
     "micromark-util-types": "^1.0.0",
-    "parse-entities": "^3.0.0"
+    "parse-entities": "^3.0.0",
+    "power-assert": "^1.0.0"
   },
   "devDependencies": {
+    "@types/power-assert": "^1.0.0",
     "@types/tape": "^4.0.0",
     "c8": "^7.0.0",
     "html-void-elements": "^2.0.0",