diff --git a/devtools/client/debugger/new/pretty-print-worker.js b/devtools/client/debugger/new/pretty-print-worker.js
index 4fa735e16e..cd9cea1726 100644
--- a/devtools/client/debugger/new/pretty-print-worker.js
+++ b/devtools/client/debugger/new/pretty-print-worker.js
@@ -1068,7 +1068,7 @@ var Debugger =
 	    // be either 3, or 5, or 6. This influences support for strict
 	    // mode, the set of reserved words, support for getters and
 	    // setters and other features.
-	    ecmaVersion: 5,
+	    ecmaVersion: 6,
 	    // Turn on `strictSemicolons` to prevent the parser from doing
 	    // automatic semicolon insertion.
 	    strictSemicolons: false,
diff --git a/devtools/shared/acorn/acorn.js b/devtools/shared/acorn/acorn.js
index 55d9a1968e..53dafa2ca6 100644
--- a/devtools/shared/acorn/acorn.js
+++ b/devtools/shared/acorn/acorn.js
@@ -1299,7 +1299,7 @@ var defaultOptions = {
   // be either 3, or 5, or 6. This influences support for strict
   // mode, the set of reserved words, support for getters and
   // setters and other features.
-  ecmaVersion: 5,
+  ecmaVersion: 6,
   // Source type ("script" or "module") for different semantics
   sourceType: "script",
   // `onInsertedSemicolon` can be a callback that will be called