diff --git a/package.json b/package.json
index c77ba81..cdb21ed 100644
--- a/package.json
+++ b/package.json
@@ -29,7 +29,7 @@
     "sanctuary-either": "2.1.x",
     "sanctuary-identity": "2.1.x",
     "sanctuary-scripts": "5.0.x",
-    "sanctuary-type-identifiers": "3.0.0",
+    "sanctuary-type-identifiers": "4.0.0",
     "sanctuary-useless": "2.0.x"
   },
   "scripts": {