diff --git a/OpenUtau.Core/Api/G2pPack.cs b/OpenUtau.Core/Api/G2pPack.cs
index 4c5b36305..ed7628720 100644
--- a/OpenUtau.Core/Api/G2pPack.cs
+++ b/OpenUtau.Core/Api/G2pPack.cs
@@ -68,7 +68,7 @@ public string[] Query(string grapheme) {
             if (grapheme.Length == 0 || kAllPunct.IsMatch(grapheme)) {
                 return null;
             }
-            var phonemes = Dict.Query(grapheme);
+            var phonemes = Dict.Query(grapheme.ToLowerInvariant());
             if (phonemes == null && !PredCache.TryGetValue(grapheme, out phonemes)) {
                 phonemes = Predict(grapheme);
                 if (phonemes.Length == 0) {
diff --git a/OpenUtau/ViewModels/PhoneticAssistantViewModel.cs b/OpenUtau/ViewModels/PhoneticAssistantViewModel.cs
index cf77ce4fa..401560c86 100644
--- a/OpenUtau/ViewModels/PhoneticAssistantViewModel.cs
+++ b/OpenUtau/ViewModels/PhoneticAssistantViewModel.cs
@@ -61,7 +61,7 @@ private void Refresh() {
                 Phonemes = string.Empty;
                 return;
             }
-            string[] phonemes = g2p.Query(Grapheme);
+            string[] phonemes = g2p.Query(Grapheme.ToLowerInvariant());
             if (phonemes == null) {
                 Phonemes = string.Empty;
                 return;