diff --git a/OpenUtau.Plugin.Builtin/KoreanCVPhonemizer.cs b/OpenUtau.Plugin.Builtin/KoreanCVPhonemizer.cs
index 3a9447701..08c0fc3af 100644
--- a/OpenUtau.Plugin.Builtin/KoreanCVPhonemizer.cs
+++ b/OpenUtau.Plugin.Builtin/KoreanCVPhonemizer.cs
@@ -192,6 +192,10 @@ private Result ConvertForCV(Note[] notes, string[] prevLyric, string[] thisLyric
             string thisMidVowelHead;
             string thisMidVowelTail;
 
+            if (kocvS == null) {
+                return GenerateResult(FindInOto(notes[0].lyric, notes[0])); // If kocvS is null, return the original lyric's phoneme
+            }
+
             int totalDuration = notes.Sum(n => n.duration);
             Note note = notes[0];
             bool isItNeedsFrontCV;
@@ -415,4 +419,4 @@ public override Result GenerateEndSound(Note[] notes, Note? prev, Note? next, No
             return GenerateResult(FindInOto($"{prevMidVowel} {endSound}", note));            
         }
     }
-}
\ No newline at end of file
+}