diff --git a/piker/data/_formatters.py b/piker/data/_formatters.py
index 53b7a070..e7bacd35 100644
--- a/piker/data/_formatters.py
+++ b/piker/data/_formatters.py
@@ -251,7 +251,6 @@ class IncrementalFormatter(msgspec.Struct):
         array_key: str,
         profiler: Profiler,
 
-        read_src_from_key: bool = True,
         slice_to_inview: bool = True,
 
     ) -> tuple[