diff --git a/Source/3rdParty/OVMandarin/Composer.mm b/Source/3rdParty/OVMandarin/Composer.mm
index 05bf391b..09379bc7 100644
--- a/Source/3rdParty/OVMandarin/Composer.mm
+++ b/Source/3rdParty/OVMandarin/Composer.mm
@@ -106,6 +106,7 @@ static Mandarin::BopomofoReadingBuffer *PhoneticBuffer;
             PhoneticBuffer->setKeyboardLayout(Mandarin::BopomofoKeyboardLayout::StandardLayout());
             mgrPrefs.mandarinParser = MandarinParserOfStandard;
         }
+        PhoneticBuffer->clear();
     }
     else
     {