diff --git a/tsconfig.json b/tsconfig.json
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -43,9 +43,11 @@
     // "noPropertyAccessFromIndexSignature": true,  /* Require undeclared properties from index signatures to use element accesses. */
 
     /* Module Resolution Options */
-    "moduleResolution": "node",                  /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */
-    // "baseUrl": "./",                             /* Base directory to resolve non-absolute module names. */
-    // "paths": {},                                 /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
+    "moduleResolution": "node"                      /* Specify module resolution strategy: 'node' (Node.js) or 'classic' (TypeScript pre-1.6). */,
+    "baseUrl": "./"                                 /* Base directory to resolve non-absolute module names. */,
+    "paths": {                                      /* A series of entries which re-map imports to lookup locations relative to the 'baseUrl'. */
+      "sylvester": ["light9/web/lib/sylvester.d.ts"]
+    },
     // "rootDirs": [],                              /* List of root folders whose combined content represents the structure of the project at runtime. */
     // "typeRoots": ["/my/proj/light9/light9/web/homepage"],                             /* List of folders to include type definitions from. */
     // "types": [],                                 /* Type declaration files to be included in compilation. */
@@ -66,6 +68,7 @@
 
     /* Advanced Options */
     "skipLibCheck": true,                           /* Skip type checking of declaration files. */
-    "forceConsistentCasingInFileNames": true        /* Disallow inconsistently-cased references to the same file. */
+    "forceConsistentCasingInFileNames": true,       /* Disallow inconsistently-cased references to the same file. */
+    "useDefineForClassFields": false
   }
 }