diff --git a/types/sharedb/tsconfig.json b/types/sharedb/tsconfig.json
index ba2f84131f..f7e3c2b8f3 100644
--- a/types/sharedb/tsconfig.json
+++ b/types/sharedb/tsconfig.json
@@ -6,7 +6,7 @@
             "dom"
         ],
         "noImplicitAny": false,
-        "noImplicitThis": false,
+        "noImplicitThis": true,
         "strictNullChecks": false,
         "strictFunctionTypes": true,
         "baseUrl": "../",
@@ -22,4 +22,4 @@
         "index.d.ts",
         "sharedb-tests.ts"
     ]
-}
\ No newline at end of file
+}