diff --git a/packages/babel-types/src/definitions/es2015.js b/packages/babel-types/src/definitions/es2015.js
index d70cebd15d..7dcfb2475a 100644
--- a/packages/babel-types/src/definitions/es2015.js
+++ b/packages/babel-types/src/definitions/es2015.js
@@ -64,6 +64,7 @@ defineType("ClassDeclaration", {
     "id",
     "body",
     "superClass",
+    "mixins",
     "typeParameters",
     "superTypeParameters",
     "implements",