diff --git a/src/ophyd_async/core/_protocol.py b/src/ophyd_async/core/_protocol.py
index 7fad73e34c..c8695a597a 100644
--- a/src/ophyd_async/core/_protocol.py
+++ b/src/ophyd_async/core/_protocol.py
@@ -101,7 +101,7 @@ def unstage(self) -> AsyncStatusBase:
 @runtime_checkable
 class AsyncMovable(Protocol[T_co]):
     @abstractmethod
-    def set(self, value: T_co) -> AsyncStatusBase:
+    def set(self, value: T_co, /) -> AsyncStatusBase:
         """Return a `Status` that is marked done when the device is done moving."""