diff --git a/Assets/VRM/Runtime/Extensions/glTF_VRMExtensions.cs b/Assets/VRM/Runtime/Extensions/glTF_VRMExtensions.cs
index 47e10a1df..7e078dd26 100644
--- a/Assets/VRM/Runtime/Extensions/glTF_VRMExtensions.cs
+++ b/Assets/VRM/Runtime/Extensions/glTF_VRMExtensions.cs
@@ -117,7 +117,7 @@ namespace VRM
             var group = new glTF_VRM_BlendShapeGroup
             {
                 name = clip.BlendShapeName,
-                presetName = clip.Preset.ToString().ToLower(),
+                presetName = clip.Preset.ToString().ToLowerInvariant(),
                 isBinary = clip.IsBinary,
                 binds = list,
                 materialValues = materialList,
diff --git a/Assets/VRM/Tests/UniVRMSerializeTests.cs b/Assets/VRM/Tests/UniVRMSerializeTests.cs
index 8809c6826..b266fa3b2 100644
--- a/Assets/VRM/Tests/UniVRMSerializeTests.cs
+++ b/Assets/VRM/Tests/UniVRMSerializeTests.cs
@@ -190,6 +190,16 @@ namespace VRM
             var json = model.ToJson();
             Assert.AreEqual(@"{""presetName"":""neutral"",""binds"":[],""materialValues"":[],""isBinary"":false}", json);
             Debug.Log(json);
+
+            // https://github.com/vrm-c/UniVRM/issues/694
+            // Must pass even if this computer's locale was tr-TR.
+            var model2 = new glTF_VRM_BlendShapeGroup()
+            {
+                presetName = "I",
+            };
+            var json2 = model2.ToJson();
+            Assert.AreEqual(@"{""presetName"":""i"",""binds"":[],""materialValues"":[],""isBinary"":false}", json2);
+            Debug.Log(json);
         }
 
         [Test]