diff --git a/experiments/procesing/steps/session.py b/experiments/procesing/steps/session.py
index cc9d99e..0c5f078 100644
--- a/experiments/procesing/steps/session.py
+++ b/experiments/procesing/steps/session.py
@@ -53,7 +53,9 @@ class TemporalFeatureStep(BaseContextStep):
             (agg['total_interactions'] / agg['session_duration_sec']) * 60, 0)
 
         vel = df.set_index('ts_dt').groupby('sessionId').resample(self.velocity_window, include_groups=False).size()
-        agg = agg.merge(vel.groupby('sessionId').max().rename('max_velocity_5min'),on='sessionId', how='left').fillna({'max_velocity_5min': 0}) # warns but its a series so whatevs
+        max_velocity = vel.groupby('sessionId').max().rename('max_velocity_5min')
+        agg = agg.merge(max_velocity, on='sessionId', how='left')
+        agg['max_velocity_5min'] = agg['max_velocity_5min'].fillna(0)
         return agg