diff --git a/Packages/vChewing_PopupCompositionBuffer/Sources/PopupCompositionBuffer/PopupCompositionBuffer.swift b/Packages/vChewing_PopupCompositionBuffer/Sources/PopupCompositionBuffer/PopupCompositionBuffer.swift
index 47f730d8..98398cef 100644
--- a/Packages/vChewing_PopupCompositionBuffer/Sources/PopupCompositionBuffer/PopupCompositionBuffer.swift
+++ b/Packages/vChewing_PopupCompositionBuffer/Sources/PopupCompositionBuffer/PopupCompositionBuffer.swift
@@ -84,6 +84,7 @@ public class PopupCompositionBuffer: NSWindowController {
         return newStyle
       }(),
     ]
+    let horizontalAttributes: [NSAttributedString.Key: Any] = [.kern: 0]
 
     if isTypingDirectionVertical {
       attrPCBHeader.setAttributes(
@@ -92,6 +93,13 @@ public class PopupCompositionBuffer: NSWindowController {
       attrString.setAttributes(
         verticalAttributes, range: NSRange(location: 0, length: attrString.length)
       )
+    } else {
+      attrPCBHeader.setAttributes(
+        horizontalAttributes, range: NSRange(location: 0, length: attrPCBHeader.length)
+      )
+      attrString.setAttributes(
+        horizontalAttributes, range: NSRange(location: 0, length: attrString.length)
+      )
     }
 
     let markerAttributes: [NSAttributedString.Key: Any] = {
@@ -144,10 +152,6 @@ public class PopupCompositionBuffer: NSWindowController {
     attrString.insert(attrPCBHeader, at: 0)
     attrString.insert(attrPCBHeader, at: attrString.length)
 
-    attrString.setAttributes(
-      [.kern: 0], range: NSRange(location: 0, length: attrString.length)
-    )
-
     textShown = attrString
     messageTextField.maximumNumberOfLines = 1
     if let editor = messageTextField.currentEditor() {