diff --git a/icecream/icecream.py b/icecream/icecream.py
index f25c6dc..3583611 100644
--- a/icecream/icecream.py
+++ b/icecream/icecream.py
@@ -483,7 +483,7 @@ def use_stderr(self) -> None:
 
     def configureOutput(
         self: "IceCreamDebugger",
-        prefix: Union[str, Literal[Sentinel.absent]] = Sentinel.absent,
+        prefix: Union[str, Callable[[], str], Literal[Sentinel.absent]] = Sentinel.absent,
         outputFunction: Union[Callable, Literal[Sentinel.absent]] = Sentinel.absent,
         argToStringFunction: Union[Callable, Literal[Sentinel.absent]] = Sentinel.absent,
         includeContext: Union[bool, Literal[Sentinel.absent]] = Sentinel.absent,