diff --git a/checkpoint_restart.dat b/checkpoint_restart.dat
new file mode 100644
index 000000000..99ed8d34d
Binary files /dev/null and b/checkpoint_restart.dat differ
diff --git a/xtrack/random/random_generators.py b/xtrack/random/random_generators.py
index cc37cea20..8256c4e8d 100644
--- a/xtrack/random/random_generators.py
+++ b/xtrack/random/random_generators.py
@@ -48,7 +48,8 @@ def generate(self, n_samples=1000, n_seeds=1000, particles=None):
         context = self._context
         n_seeds = int(n_seeds)
         if particles is None:
-            particles = xp.Particles(state=np.ones(n_seeds), _context=context)
+            particles = xp.Particles(state=np.ones(n_seeds),
+                                     x=np.ones(n_seeds), _context=context)
         elif n_seeds != len(particles._rng_s1):
             print("Warning: both 'particles' and 'n_seeds' are given, but "
                   + "are not compatible. Ignoring 'n_seeds'...")