diff --git a/Runtime/Plugins/GLTFSerialization/Schema/GLTFMaterial.cs b/Runtime/Plugins/GLTFSerialization/Schema/GLTFMaterial.cs
index bb3dffe34..565de212b 100644
--- a/Runtime/Plugins/GLTFSerialization/Schema/GLTFMaterial.cs
+++ b/Runtime/Plugins/GLTFSerialization/Schema/GLTFMaterial.cs
@@ -219,7 +219,8 @@ public override void Serialize(JsonWriter writer)
 			if (AlphaCutoff != 0.5)
 			{
 				writer.WritePropertyName("alphaCutoff");
-				writer.WriteValue(AlphaCutoff);
+				var sanitizedCutoff = AlphaCutoff < 0.0 ? 0.0 : AlphaCutoff > 1.0 ? 1.0 : AlphaCutoff;
+				writer.WriteValue(sanitizedCutoff);
 			}
 
 			if (DoubleSided)