diff --git a/mbtrack2/tracking/particles.py b/mbtrack2/tracking/particles.py
index a96919fd71ebe6d2d2ebcc334ad4109535467728..0d819a81913ccc0d278f2fa102306157374aa048 100644
--- a/mbtrack2/tracking/particles.py
+++ b/mbtrack2/tracking/particles.py
@@ -287,7 +287,8 @@ class Bunch:
         cov_y = np.cov(self['y'], self['yp'])
         cov_z = np.cov(self['tau'], self['delta'])
 
-        if (np.array(self.ring.optics.local_dispersion) != np.array([0, 0, 0, 0])).all():
+        if (np.array(self.ring.optics.local_dispersion)
+                != np.array([0, 0, 0, 0])).all():
             cov_xdelta = np.cov(self['x'], self['delta'])
             cov_xpdelta = np.cov(self['xp'], self['delta'])
             cov_ydelta = np.cov(self['y'], self['delta'])