diff --git a/dpdata/lammps/dump.py b/dpdata/lammps/dump.py
index 1af637d35..06da27c81 100644
--- a/dpdata/lammps/dump.py
+++ b/dpdata/lammps/dump.py
@@ -178,7 +178,7 @@ def system_data(lines, type_map = None, type_idx_zero = True) :
         bounds, tilt = get_dumpbox(array_lines[ii])
         orig, cell = dumpbox2box(bounds, tilt)
         system['cells'].append(cell)
-        system['coords'].append(safe_get_posi(lines, cell) - np.array(orig))
+        system['coords'].append(safe_get_posi(array_lines[ii], cell) - np.array(orig))
     system['cells'] = np.array(system['cells'])
     system['coords'] = np.array(system['coords'])
     return system