diff --git a/hamilflow/models/brownian_motion.py b/hamilflow/models/brownian_motion.py
index 25bcd64..7ffe140 100644
--- a/hamilflow/models/brownian_motion.py
+++ b/hamilflow/models/brownian_motion.py
@@ -206,8 +206,6 @@ def __call__(self, t: TypeTime, seed: int = 42) -> pd.DataFrame:
         n_steps = np.array(t).size
         trajectory = self._trajectory(n_new_steps=n_steps - 1, seed=seed)
 
-        df = pd.DataFrame(trajectory, columns=self._axis_names)
-
-        df["t"] = t
+        df = pd.DataFrame(trajectory, columns=self._axis_names).assign(t=t)
 
         return df