diff --git a/package.json b/package.json
index 2a7483d..40f177b 100644
--- a/package.json
+++ b/package.json
@@ -40,7 +40,7 @@
     "rollup": "~1.18",
     "sanctuary-scripts": "^3.2.0",
     "sanctuary-show": "^1.0.0",
-    "sanctuary-type-classes": "^11.0.0",
+    "sanctuary-type-classes": "^12.0.0",
     "sinon": "^7.1.0"
   }
 }