diff --git a/runpod/serverless/__init__.py b/runpod/serverless/__init__.py
index 7c238150..62f70722 100644
--- a/runpod/serverless/__init__.py
+++ b/runpod/serverless/__init__.py
@@ -172,16 +172,15 @@ def start(config: Dict[str, Any]):
         return
 
     # --------------------------------- SLS-Core --------------------------------- #
-    if os.getenv("RUNPOD_SLS_CORE", "false").lower() in (
-        "1",
-        "t",
-        "T",
-        "TRUE",
-        "true",
-        "True",
-    ):
-        core.main(config)
-        return
+
+    if os.getenv("RUNPOD_SLS_CORE") is None and os.getenv("RUNPOD_USE_CORE") is not None:
+            log.warn("RUNPOD_USE_CORE is deprecated. Please use RUNPOD_SLS_CORE instead.")
+            core.main(config)
+            return
+
+    elif os.getenv("RUNPOD_SLS_CORE","false").lower() in ["1", "t", "true"]:
+            core.main(config)
+            return
 
     # --------------------------------- Standard --------------------------------- #
     worker.main(config)