diff --git a/dev/lib/syntax.js b/dev/lib/syntax.js
index 07b9903..862913e 100644
--- a/dev/lib/syntax.js
+++ b/dev/lib/syntax.js
@@ -16,7 +16,7 @@
  *   GFM spec.
  */
 
-import assert from 'power-assert'
+import {ok as assert} from 'uvu/assert'
 import {splice} from 'micromark-util-chunked'
 import {classifyCharacter} from 'micromark-util-classify-character'
 import {resolveAll} from 'micromark-util-resolve-all'
diff --git a/package.json b/package.json
index 5a7f679..363d1b7 100644
--- a/package.json
+++ b/package.json
@@ -46,10 +46,9 @@
     "micromark-util-resolve-all": "^1.0.0",
     "micromark-util-symbol": "^1.0.0",
     "micromark-util-types": "^1.0.0",
-    "power-assert": "^1.0.0"
+    "uvu": "^0.5.0"
   },
   "devDependencies": {
-    "@types/power-assert": "^1.0.0",
     "@types/tape": "^4.0.0",
     "c8": "^7.0.0",
     "micromark": "^3.0.0",
@@ -81,6 +80,7 @@
   "xo": {
     "prettier": true,
     "rules": {
+      "node/file-extension-in-import": "off",
       "unicorn/prefer-node-protocol": "off"
     }
   },