diff --git a/Source/Modules/IMEModules/ctlInputMethod.swift b/Source/Modules/IMEModules/ctlInputMethod.swift
index 5e677281..bfe39811 100644
--- a/Source/Modules/IMEModules/ctlInputMethod.swift
+++ b/Source/Modules/IMEModules/ctlInputMethod.swift
@@ -260,8 +260,20 @@ extension ctlInputMethod {
     if buffer.isEmpty {
       return
     }
+
+    var bufferOutput = ""
+
+    // 防止輸入法輸出不可列印的字元。
+    for theChar in buffer {
+      if let charCode = theChar.utf16.first {
+        if !(theChar.isASCII && !(charCode.isPrintable())) {
+          bufferOutput += String(theChar)
+        }
+      }
+    }
+
     (client as? IMKTextInput)?.insertText(
-      buffer, replacementRange: NSRange(location: NSNotFound, length: NSNotFound)
+      bufferOutput, replacementRange: NSRange(location: NSNotFound, length: NSNotFound)
     )
   }