diff --git a/src/polyfills/symbols.js b/src/polyfills/symbols.js
index f7e532e45b..e13d8b4f3a 100644
--- a/src/polyfills/symbols.js
+++ b/src/polyfills/symbols.js
@@ -1,13 +1,19 @@
 // In ES2015 (or a polyfilled) environment, this will be Symbol.iterator
 // istanbul ignore next (See: 'https://github.com/graphql/graphql-js/issues/2317')
 export const SYMBOL_ITERATOR: string =
-  typeof Symbol === 'function' ? Symbol.iterator : '@@iterator';
+  typeof Symbol === 'function' && Symbol.iterator != null
+    ? Symbol.iterator
+    : '@@iterator';
 
 // In ES2017 (or a polyfilled) environment, this will be Symbol.asyncIterator
 // istanbul ignore next (See: 'https://github.com/graphql/graphql-js/issues/2317')
 export const SYMBOL_ASYNC_ITERATOR: string =
-  typeof Symbol === 'function' ? Symbol.asyncIterator : '@@asyncIterator';
+  typeof Symbol === 'function' && Symbol.asyncIterator != null
+    ? Symbol.asyncIterator
+    : '@@asyncIterator';
 
 // istanbul ignore next (See: 'https://github.com/graphql/graphql-js/issues/2317')
 export const SYMBOL_TO_STRING_TAG: string =
-  typeof Symbol === 'function' ? Symbol.toStringTag : '@@toStringTag';
+  typeof Symbol === 'function' && Symbol.toStringTag != null
+    ? Symbol.toStringTag
+    : '@@toStringTag';