diff --git a/modal/functions.py b/modal/functions.py
index 0aa63b1a2..0b58ae865 100644
--- a/modal/functions.py
+++ b/modal/functions.py
@@ -1275,6 +1275,10 @@ async def _call_generator(self, args, kwargs):
 
     @synchronizer.no_io_translation
     async def _call_generator_nowait(self, args, kwargs):
+        deprecation_warning(
+            (2024, 12, 11),
+            "Calling spawn on a generator function is deprecated and will soon be removed.",
+        )
         return await _Invocation.create(
             self,
             args,