diff --git a/package.json b/package.json
index d2589c0..433cf01 100644
--- a/package.json
+++ b/package.json
@@ -89,7 +89,7 @@
     "@types/node": "^20.1.1",
     "bdd-lazy-var": "^2.5.4",
     "chai": "^4.3.6",
-    "chai-as-promised": "^7.1.1",
+    "chai-as-promised": "^8.0.2",
     "eslint": "^8.11.0",
     "eslint-config-nicenice": "^3.0.0",
     "eslint-config-standard": "^17.0.0",
diff --git a/test/environment.js b/test/environment.js
index 33292af..eb4b1f7 100644
--- a/test/environment.js
+++ b/test/environment.js
@@ -1,7 +1,8 @@
 const sinon = require('sinon')
 const chai = require('chai')
 const sinonChai = require('sinon-chai')
-const chaiAsPromised = require('chai-as-promised')
+// chai-as-promised 8 is ESM-only, so require() returns its module namespace
+const chaiAsPromised = require('chai-as-promised').default
 
 chai.use(sinonChai)
 chai.use(chaiAsPromised)
diff --git a/yarn.lock b/yarn.lock
index d2d726d..096ea62 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -35,7 +35,7 @@ __metadata:
     "@types/node": "npm:^20.1.1"
     bdd-lazy-var: "npm:^2.5.4"
     chai: "npm:^4.3.6"
-    chai-as-promised: "npm:^7.1.1"
+    chai-as-promised: "npm:^8.0.2"
     eslint: "npm:^8.11.0"
     eslint-config-nicenice: "npm:^3.0.0"
     eslint-config-standard: "npm:^17.0.0"
@@ -2375,14 +2375,14 @@ __metadata:
   languageName: node
   linkType: hard
 
-"chai-as-promised@npm:^7.1.1":
-  version: 7.1.1
-  resolution: "chai-as-promised@npm:7.1.1"
+"chai-as-promised@npm:^8.0.2":
+  version: 8.0.2
+  resolution: "chai-as-promised@npm:8.0.2"
   dependencies:
-    check-error: "npm:^1.0.2"
+    check-error: "npm:^2.1.1"
   peerDependencies:
-    chai: ">= 2.1.2 < 5"
-  checksum: 10c0/e25a602c3a8cd0b97ce6b0c7ddaaf4bd8517941da9f44dc65262c5268ea463f634dc495cdef6a21eaeffdb5022b6f4c3781027b8308273b7fff089c605abf6aa
+    chai: ">= 2.1.2 < 7"
+  checksum: 10c0/829bcd98c04f0b108b2f7379efd33c668e53fbf0bda8d460dc63c96a709fd5de79909392aa78b4256de16a4d57640641d7affc516111e371d6e9f6aec1cc6c8a
   languageName: node
   linkType: hard
 
@@ -2422,7 +2422,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"check-error@npm:^1.0.2, check-error@npm:^1.0.3":
+"check-error@npm:^1.0.3":
   version: 1.0.3
   resolution: "check-error@npm:1.0.3"
   dependencies:
@@ -2431,6 +2431,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"check-error@npm:^2.1.1":
+  version: 2.1.3
+  resolution: "check-error@npm:2.1.3"
+  checksum: 10c0/878e99038fb6476316b74668cd6a498c7e66df3efe48158fa40db80a06ba4258742ac3ee2229c4a2a98c5e73f5dff84eb3e50ceb6b65bbd8f831eafc8338607d
+  languageName: node
+  linkType: hard
+
 "chokidar@npm:^3.4.0, chokidar@npm:^3.5.2":
   version: 3.5.3
   resolution: "chokidar@npm:3.5.3"