diff --git a/src/optimise/train.jl b/src/optimise/train.jl
index c57f093f..fbfb5670 100644
--- a/src/optimise/train.jl
+++ b/src/optimise/train.jl
@@ -18,7 +18,7 @@ struct StopException <: Exception
   x::Symbol
 end
 
-function stop(x)
+function stop()
   throw(StopException())
 end