diff --git a/app/backend/app.py b/app/backend/app.py
index 9b2128bd51..c1948123dd 100644
--- a/app/backend/app.py
+++ b/app/backend/app.py
@@ -328,7 +328,7 @@ async def setup_clients():
         query_speller=AZURE_SEARCH_QUERY_SPELLER,
     )
 
-    if AZURE_OPENAI_GPT4V_MODEL:
+    if USE_GPT4V:
         if vision_key is None:
             raise ValueError("Vision key must be set (in Key Vault) to use the vision approach.")
 
diff --git a/tests/conftest.py b/tests/conftest.py
index 8d63802e9e..67e13e0889 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -235,6 +235,7 @@ def mock_blob_container_client(monkeypatch):
         "AZURE_OPENAI_SERVICE": "test-openai-service",
         "AZURE_OPENAI_CHATGPT_DEPLOYMENT": "test-chatgpt",
         "AZURE_OPENAI_EMB_DEPLOYMENT": "test-ada",
+        "USE_GPT4V": "true",
         "AZURE_OPENAI_GPT4V_MODEL": "gpt-4",
         "VISION_SECRET_NAME": "mysecret",
         "VISION_ENDPOINT": "https://testvision.cognitiveservices.azure.com/",