diff --git a/examples/code-highlighting/index.js b/examples/code-highlighting/index.js
index 57d616903..70461d7d1 100644
--- a/examples/code-highlighting/index.js
+++ b/examples/code-highlighting/index.js
@@ -70,12 +70,13 @@ function codeBlockDecorator(text, block) {
 
     const length = offset + token.content.length
     const type = `highlight-${token.type}`
+    const mark = Mark.create({ type })
 
     for (let i = offset; i < length; i++) {
       let char = characters.get(i)
       let { marks } = char
-      marks = marks.add(Mark.create({ type }))
-      char = char.merge({ marks })
+      marks = marks.add(mark)
+      char = char.set('marks', marks)
       characters.set(i, char)
     }
 
diff --git a/examples/markdown-preview/index.js b/examples/markdown-preview/index.js
index f7a18db62..99d50c844 100644
--- a/examples/markdown-preview/index.js
+++ b/examples/markdown-preview/index.js
@@ -41,7 +41,7 @@ function addMarks(characters, tokens, offset) {
       let char = characters.get(i)
       let { marks } = char
       marks = marks.add(mark)
-      char = char.merge({ marks })
+      char = char.set('marks', marks)
       characters.set(i, char)
     }