diff --git a/tsconfig.json b/tsconfig.json
index 859909e..f8ab778 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -5,6 +5,7 @@
     "declaration": true,
     "emitDecoratorMetadata": true,
     "experimentalDecorators": true,
+    "keyofStringsOnly": true,
     "mapRoot": "./dist/",
     "module": "commonjs",
     "moduleResolution": "node",
@@ -15,7 +16,10 @@
       "node_modules/@types"
     ]
   },
-  "include": ["test/**/*", "src/**/*"],
+  "include": [
+    "test/**/*",
+    "src/**/*"
+  ],
   "exclude": [
     "dist",
     "node_modules"