diff --git a/forest/benchmarking/distance_measures.py b/forest/benchmarking/distance_measures.py
index ab59b137..1bb06f6e 100644
--- a/forest/benchmarking/distance_measures.py
+++ b/forest/benchmarking/distance_measures.py
@@ -111,7 +111,7 @@ def trace_distance(rho: np.ndarray, sigma: np.ndarray) -> float:
     :param sigma: Is a dim by dim positive matrix with unit trace.
     :return: Trace distance which is a scalar.
     """
-    return (0.5) * np.linalg.norm(rho - sigma, 1)
+    return (0.5) * np.linalg.norm(rho - sigma, 'nuc')
 
 
 def bures_distance(rho: np.ndarray, sigma: np.ndarray) -> float: