diff --git a/src/spikeinterface/preprocessing/filter.py b/src/spikeinterface/preprocessing/filter.py
index e66797f93e..758d853aee 100644
--- a/src/spikeinterface/preprocessing/filter.py
+++ b/src/spikeinterface/preprocessing/filter.py
@@ -353,6 +353,7 @@ class CausalFilter(FilterRecording):
         If true, filtering is applied in just one direction.
     direction : "forward" | "backward", default: "forward"
         when causal_mode = True, defines the direction of the filtering
+
     Returns
     -------
     filter_recording : CausalFilterRecording