diff --git a/src/environment/ReactServerRendering.js b/src/environment/ReactServerRendering.js
index 9c67e880ea..d0750653fc 100644
--- a/src/environment/ReactServerRendering.js
+++ b/src/environment/ReactServerRendering.js
@@ -27,7 +27,7 @@ var invariant = require('invariant');
 
 /**
  * @param {ReactComponent} component
- * @return {String} the markup
+ * @return {string} the markup
  */
 function renderComponentToString(component) {
   invariant(