diff --git a/galsec.py b/galsec.py
index ed54234..a640c34 100644
--- a/galsec.py
+++ b/galsec.py
@@ -332,9 +332,9 @@ class Galsec:
              spacing between two y bins
         """
         for fluid in self.fluids:
-            x_bin = np.trunc(self.data[fluid]["position"][:, 0] / delta_x)
-            y_bin = np.trunc(self.data[fluid]["position"][:, 1] / delta_y)
-            z_bin = np.trunc(self.data[fluid]["position"][:, 2] / delta_z)
+            x_bin = np.floor(self.data[fluid]["position"][:, 0] / delta_x)
+            y_bin = np.floor(self.data[fluid]["position"][:, 1] / delta_y)
+            z_bin = np.floor(self.data[fluid]["position"][:, 2] / delta_z)
             self.data[fluid]["x_bin"] = (x_bin + 0.5) * delta_x  # Store the middle value
             self.data[fluid]["y_bin"] = (y_bin + 0.5) * delta_y  # Store the middle value
             self.data[fluid]["z_bin"] = (z_bin + 0.5) * delta_z  # Store the middle value