diff --git a/Marker3.0/AnimationGenerator/Editor/SnailMarker3AnimationCreatorEditor.cs b/Marker3.0/AnimationGenerator/Editor/SnailMarker3AnimationCreatorEditor.cs
index 0a9f686..98ef8df 100644
--- a/Marker3.0/AnimationGenerator/Editor/SnailMarker3AnimationCreatorEditor.cs
+++ b/Marker3.0/AnimationGenerator/Editor/SnailMarker3AnimationCreatorEditor.cs
@@ -116,7 +116,7 @@ private void ShowMenuFoldout(VRCExpressionsMenu menu, string title)
                         {
                             newParams[i] = expressionParams.parameters[i];
                         }
-
+                        newParams[expressionParams.parameters.Length] = new VRCExpressionParameters.Parameter();
                         expressionParams.parameters = newParams;
                         EditorUtility.SetDirty(expressionParams);
                     }