diff --git a/openflexure_microscope/api/default_extensions/scan.py b/openflexure_microscope/api/default_extensions/scan.py
index a5f82f52..ef788a05 100644
--- a/openflexure_microscope/api/default_extensions/scan.py
+++ b/openflexure_microscope/api/default_extensions/scan.py
@@ -198,6 +198,7 @@ def tile(
                 else:
                     # Run slow autofocus. Client should provide dz ~ 50
                     autofocus_extension.autofocus(
+                        microscope,
                         range(-3 * autofocus_dz, 4 * autofocus_dz, autofocus_dz)
                     )
                     logging.debug("Finished autofocus")