diff --git a/server/text_generation_server/utils/watermark.py b/server/text_generation_server/utils/watermark.py
index df7b90e3..5d8f5312 100644
--- a/server/text_generation_server/utils/watermark.py
+++ b/server/text_generation_server/utils/watermark.py
@@ -19,8 +19,8 @@ import torch
 from transformers import LogitsProcessor
 from typing import List, Union
 
-GAMMA = os.getenv("WATERMARK_GAMMA", 0.5)
-DELTA = os.getenv("WATERMARK_DELTA", 2.0)
+GAMMA = float(os.getenv("WATERMARK_GAMMA", 0.5))
+DELTA = float(os.getenv("WATERMARK_DELTA", 2.0))
 
 
 class WatermarkLogitsProcessor(LogitsProcessor):