diff --git a/src/Panel.jsx b/src/Panel.jsx
index 8acc74ce..841c49d9 100644
--- a/src/Panel.jsx
+++ b/src/Panel.jsx
@@ -21,7 +21,9 @@ class CollapsePanel extends Component {
       showArrow,
       destroyInactivePanel,
     } = this.props;
-    const headerCls = `${prefixCls}-header ${headerClass}`;
+    const headerCls = classNames(`${prefixCls}-header`, {
+      [headerClass]: headerClass,
+    });
     const itemCls = classNames({
       [`${prefixCls}-item`]: true,
       [`${prefixCls}-item-active`]: isActive,