diff --git a/scripts/build.js b/scripts/build.js
index 129d760..8afcd77 100755
--- a/scripts/build.js
+++ b/scripts/build.js
@@ -53,11 +53,14 @@ const build = () => {
             ], callback);
           });
         });
+      },
+      (callback) => {
+        fs.createReadStream('./src/index.d.ts')
+          .pipe(fs.createWriteStream('./lib/index.d.ts'))
+          .on('finish', callback);
       }
     ], () => { console.log('Build complete.')});
   });
-
-  fs.createReadStream('./src/index.d.ts').pipe(fs.createWriteStream('./lib/index.d.ts'));
 };
 
 if (argv.watch) {