diff --git a/src/instance.ts b/src/instance.ts
index d3f9e0b..4be8bf2 100644
--- a/src/instance.ts
+++ b/src/instance.ts
@@ -364,7 +364,7 @@ export function readConfigFile(
 	}
 }
 
-let EXTENSIONS = /\.tsx?$|\.jsx?$/
+let EXTENSIONS = /\.tsx?$|\.jsx?$|\.json$/
 export type Dict<T> = { [key: string]: T }
 
 const filterMtimes = (mtimes: any) => {