diff --git a/src/index.js b/src/index.js
index 9892d218..a38332ac 100644
--- a/src/index.js
+++ b/src/index.js
@@ -209,6 +209,9 @@ function _renderToString(vnode, context, isSvgMode, selectValue, parent) {
 		}
 		return rendered;
 	}
+	
+	// VNodes have {constructor:undefined} to prevent JSON injection:
+	if (vnode.constructor !== undefined) return '';
 
 	vnode[PARENT] = parent;
 	if (options[DIFF]) options[DIFF](vnode);