replicate react sources

mui · Sep 6, 2019 · ecc4179 · ecc4179
1 parent d7d41ae
commit ecc4179
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/packages/material-ui-styles/src/ThemeProvider/nested.js b/packages/material-ui-styles/src/ThemeProvider/nested.js
@@ -1,3 +1,3 @@
-const hasSymbol = typeof Symbol === 'function';
+const hasSymbol = typeof Symbol === 'function' && Symbol.for;
 
-export default (hasSymbol && Symbol.for ? Symbol.for('mui.nested') : '__THEME_NESTED__');
+export default (hasSymbol ? Symbol.for('mui.nested') : '__THEME_NESTED__');