diff --git a/backend/server/models.py b/backend/server/models.py
index 8cfce45..7cdb43b 100644
--- a/backend/server/models.py
+++ b/backend/server/models.py
@@ -14,7 +14,7 @@ def get_supported_models():
             "chat_model": ChatOpenAI(model="gpt-3.5-turbo", temperature=0),
             "description": "GPT-3.5 Turbo",
         }
-        if os.environ.get("DISABLE_GPT4").lower() != "true":
+        if os.environ.get("DISABLE_GPT4", "").lower() != "true":
             models["gpt-4-0125-preview"] = {
                 "chat_model": ChatOpenAI(model="gpt-4-0125-preview", temperature=0),
                 "description": "GPT-4 0125 Preview",