diff --git a/navipy/moving/agent.py b/navipy/moving/agent.py
index 64260231ff6a500bb67fde6b88bb4070585c9fb9..65f2dde1883f141c33f6d86ccf6c101a8652bc1c 100644
--- a/navipy/moving/agent.py
+++ b/navipy/moving/agent.py
@@ -394,7 +394,7 @@ the agent motion, or
                            filename=None,
                            blocksize=100):
         if os.path.exists(filename):
-            self.velocities = pd.read_hdf()
+            self.velocities = pd.read_hdf(filename)
         nodes_tocompute = self.velocities.isna().any(axis=1)
         nodes_tocompute = nodes_tocompute[nodes_tocompute].index
         # Build a list of nodes