diff --git a/gptc/model.py b/gptc/model.py
index b9613d3..845c3f6 100644
--- a/gptc/model.py
+++ b/gptc/model.py
@@ -120,7 +120,7 @@ class Model:
         }
 
     def serialize(self, file: BinaryIO) -> None:
-        file.write(b"GPTC model v5\n")
+        file.write(b"GPTC model v6\n")
         file.write(
             json.dumps(
                 {
@@ -154,7 +154,7 @@ class TransparentConfidences(Confidences):
 
 def deserialize(encoded_model: BinaryIO) -> Model:
     prefix = encoded_model.read(14)
-    if prefix != b"GPTC model v5\n":
+    if prefix != b"GPTC model v6\n":
         raise InvalidModelError()
 
     config_json = b""