diff --git a/src/core/ReactCompositeComponent.js b/src/core/ReactCompositeComponent.js
index 308181025b7..9229fe66c71 100644
--- a/src/core/ReactCompositeComponent.js
+++ b/src/core/ReactCompositeComponent.js
@@ -95,7 +95,7 @@ var ReactCompositeComponentInterface = {
    * @type {object}
    * @optional
    */
-  propTypes: SpecPolicy.DEFINE_ONCE,
+  propTypes: SpecPolicy.DEFINE_MANY_MERGED,