diff --git a/scripts/postinstall.js b/scripts/postinstall.js
index d2f044101..f14f177aa 100644
--- a/scripts/postinstall.js
+++ b/scripts/postinstall.js
@@ -24,7 +24,7 @@ npm.on("close", function(code) {
     console.log("serialport installation failed. Error Code:", code);
   }
 
-  delete process.ENV.SERIAL_PORT_INSTALLED;
+  delete process.env.SERIAL_PORT_INSTALLED;
 });
 
 /*
diff --git a/scripts/preinstall.js b/scripts/preinstall.js
index 8d7299651..d7b9f3655 100644
--- a/scripts/preinstall.js
+++ b/scripts/preinstall.js
@@ -1 +1 @@
-process.ENV.SERIAL_PORT_INSTALLED = true;
+process.env.SERIAL_PORT_INSTALLED = true;