diff --git a/src/jsutils/instanceOf.js b/src/jsutils/instanceOf.js
index 6b7c17576b..d45b58f0f0 100644
--- a/src/jsutils/instanceOf.js
+++ b/src/jsutils/instanceOf.js
@@ -11,7 +11,7 @@ declare function instanceOf(
 
 // See: https://expressjs.com/en/advanced/best-practice-performance.html#set-node_env-to-production
 // See: https://webpack.js.org/guides/production/
-export default isProductionEnvironment()
+export default process.env.NODE_ENV === 'production'
   ? // istanbul ignore next (See: 'https://github.com/graphql/graphql-js/issues/2317')
     // eslint-disable-next-line no-shadow
     function instanceOf(value: mixed, constructor: mixed) {
@@ -44,28 +44,3 @@ spurious results.`,
       }
       return false;
     };
-
-/* global Deno */
-/* :: declare var Deno: any; */
-
-function isProductionEnvironment() {
-  // istanbul ignore next (See: 'https://github.com/graphql/graphql-js/issues/2317')
-  try {
-    if (process.env.NODE_ENV === 'production') {
-      return true;
-    }
-  } catch (e) {
-    // ignore
-  }
-
-  // istanbul ignore next (See: 'https://github.com/graphql/graphql-js/issues/2317')
-  try {
-    if (Deno.env.get('DENO_ENV') === 'production') {
-      return true;
-    }
-  } catch (e) {
-    // ignore
-  }
-
-  return false;
-}