diff --git a/packages/okidoc-md/src/utils/nodeAST.js b/packages/okidoc-md/src/utils/nodeAST.js
index <HASH>..<HASH> 100644
--- a/packages/okidoc-md/src/utils/nodeAST.js
+++ b/packages/okidoc-md/src/utils/nodeAST.js
@@ -56,6 +56,7 @@ function cleanUpClassProperty(
   // https://github.com/babel/babel/blob/v7.0.0-beta.44/packages/babel-plugin-transform-typescript/src/index.js#L155-L168
   node.accessibility = null;
   node.decorators = [];
+  item.optional = false;
 
   cleanUpNodeJSDoc(node, JSDocCommentValue);
 }
fix(okidoc-md): fix issue ts vs flow issue for optional class property