diff --git a/dev/index.php b/dev/index.php
index 72be40e..632f8c2 100644
--- a/dev/index.php
+++ b/dev/index.php
@@ -55,6 +55,7 @@
 		</style>
 		
 		<script type="text/javascript"><?php
+			"use strict";
 			foreach(scandir("../src/helper") as $one_file){
 				if(is_file("../src/helper/" . $one_file)){
 					require("../src/helper/" . $one_file);
diff --git a/src/helper/enum.js b/src/helper/enum.js
index 58ed659..cbaee8d 100644
--- a/src/helper/enum.js
+++ b/src/helper/enum.js
@@ -1,4 +1,3 @@
-"use strict";
 class Juicescript_helper_enum {
 	constructor(...keys){
 		keys.forEach((key, i) => {
diff --git a/src/io.js b/src/io.js
index 6c0b163..47aa520 100644
--- a/src/io.js
+++ b/src/io.js
@@ -1,4 +1,3 @@
-"use strict";
 class Juicescript_io {
 	/*
 		CONSTRUCTOR: Return new juicescript io adapter with CALLBACKs
diff --git a/src/lexer.js b/src/lexer.js
index 1fc6e8a..8396f44 100644
--- a/src/lexer.js
+++ b/src/lexer.js
@@ -1,4 +1,3 @@
-"use strict";
 class Juicescript_lexer {
 	/*
 		CONSTRUCTOR: Return new juicescript lexer for SOURCE with OPTIONS
diff --git a/src/main.js b/src/main.js
index 4b5f608..98170c7 100644
--- a/src/main.js
+++ b/src/main.js
@@ -1,4 +1,3 @@
-"use strict";
 class Juicescript {
 	// TOKEN TYPES //
 	static token_type = new Juicescript_helper_enum(