diff --git a/lib/es6.js b/lib/es6.js
index 32ed19f..cfca058 100644
--- a/lib/es6.js
+++ b/lib/es6.js
@@ -1,5 +1,5 @@
-let shouldAssert = process.env.NODE_ENV === "development",
-    assert, assertType;
+let assert, assertType;
+const shouldAssert = process.env.NODE_ENV === "development";
 
 if (shouldAssert) {
   ({ assert, assertType } = require("yaassertion"));
diff --git a/lib/es7.js b/lib/es7.js
index 8e75158..70c6fd7 100644
--- a/lib/es7.js
+++ b/lib/es7.js
@@ -1,5 +1,5 @@
-let shouldAssert = process.env.NODE_ENV === "development",
-    assert, assertType;
+let assert, assertType;
+const shouldAssert = process.env.NODE_ENV === "development";
 
 if (shouldAssert) {
   ({ assert, assertType } = require("yaassertion"));