diff --git a/package.json b/package.json
index 66cd4eb..3ebf850 100644
--- a/package.json
+++ b/package.json
@@ -14,7 +14,7 @@
 		"node": ">=10"
 	},
 	"scripts": {
-		"test": "xo && ava",
+		"test": "xo && ava && tsd",
 		"optimization-test": "node --allow-natives-syntax optimization-test.js"
 	},
 	"files": [