diff --git a/lib/rules/prop-types.js b/lib/rules/prop-types.js
index ec909f2792..b4d77ddc3f 100644
--- a/lib/rules/prop-types.js
+++ b/lib/rules/prop-types.js
@@ -580,7 +580,9 @@ module.exports = function(context) {
         }
       }
 
-      markPropTypesAsDeclared(node, node.value.body.body[i].argument);
+      if (i >= 0) {
+        markPropTypesAsDeclared(node, node.value.body.body[i].argument);
+      }
     },
 
     ObjectExpression: function(node) {