diff --git a/README.md b/README.md
index d15fcc4..73af828 100644
--- a/README.md
+++ b/README.md
@@ -6,5 +6,6 @@ To build and run the prototype, run:
 
 ```
 npx tsc
+echo '{"type": "module"}' > obj/package.json
 node obj
 ```
diff --git a/package.json5 b/package.json5
index 874d5e3..9cfd021 100644
--- a/package.json5
+++ b/package.json5
@@ -18,6 +18,8 @@
       url: 'https://code.studioinfinity.org/glen/typocomath.git',
    },
    devDependencies: {
-      typescript: '^4.9.3',
+      '@types/node': '^20.5.0',
+      'source-map': '^0.7.4',
+      typescript: '^5.1.6',
    },
 }
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 095704b..682e112 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -1,15 +1,33 @@
-lockfileVersion: 5.4
+lockfileVersion: '6.0'
 
-specifiers:
-  typescript: ^4.9.3
+settings:
+  autoInstallPeers: true
+  excludeLinksFromLockfile: false
 
 devDependencies:
-  typescript: 4.9.3
+  '@types/node':
+    specifier: ^20.5.0
+    version: 20.5.0
+  source-map:
+    specifier: ^0.7.4
+    version: 0.7.4
+  typescript:
+    specifier: ^5.1.6
+    version: 5.1.6
 
 packages:
 
-  /typescript/4.9.3:
-    resolution: {integrity: sha512-CIfGzTelbKNEnLpLdGFgdyKhG23CKdKgQPOBc+OUNrkJ2vr+KSzsSV5kq5iWhEQbok+quxgGzrAtGWCyU7tHnA==}
-    engines: {node: '>=4.2.0'}
+  /@types/node@20.5.0:
+    resolution: {integrity: sha512-Mgq7eCtoTjT89FqNoTzzXg2XvCi5VMhRV6+I2aYanc6kQCBImeNaAYRs/DyoVqk1YEUJK5gN9VO7HRIdz4Wo3Q==}
+    dev: true
+
+  /source-map@0.7.4:
+    resolution: {integrity: sha512-l3BikUxvPOcn5E74dZiq5BGsTb5yEwhaTSzccU6t4sDOH8NWJCstKO5QT2CvtFoK6F0saL7p9xHAqHOlCPJygA==}
+    engines: {node: '>= 8'}
+    dev: true
+
+  /typescript@5.1.6:
+    resolution: {integrity: sha512-zaWCozRZ6DLEWAWFrVDz1H6FVXzUSfTy5FUMWsQlU8Ym5JP9eO4xkTIROFCQvhQf61z6O/G6ugw3SgAnvvm+HA==}
+    engines: {node: '>=14.17'}
     hasBin: true
     dev: true
diff --git a/src/generic/arithmetic.ts b/src/generic/arithmetic.ts
index 78ad57d..6f4e949 100644
--- a/src/generic/arithmetic.ts
+++ b/src/generic/arithmetic.ts
@@ -3,3 +3,5 @@ import type {Dependencies, Signature} from '../interfaces/type.js'
 export const square =
    <T>(dep: Dependencies<'multiply', T>): Signature<'square', T> =>
    z => dep.multiply(z, z)
+   // z => dep.fooBar(z, z) // fails as desired
+   // z => dep.multiply(z, 'foo') // fails as desired
diff --git a/tsconfig.json b/tsconfig.json
index aae3a94..b45999b 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -2,6 +2,7 @@
     "compilerOptions": {
         "target": "ES2022",
         "rootDir": "./src",
-        "outDir": "./obj"
+        "outDir": "./obj",
+        "moduleResolution": "nodenext"
     }
 }