diff --git a/pyerrors/pyerrors.py b/pyerrors/pyerrors.py
index a87185d7..6c6a1130 100644
--- a/pyerrors/pyerrors.py
+++ b/pyerrors/pyerrors.py
@@ -852,12 +852,12 @@ def covariance(obs1, obs2, correlation=False, **kwargs):
 
             r_length.append(len(obs1.deltas[r_name]))
 
-            gamma += np.sum(obs1.deltas[r_name] * obs2.deltas[r_name]) / len(obs1.deltas[r_name])
+            gamma += np.sum(obs1.deltas[r_name] * obs2.deltas[r_name])
 
         e_N = np.sum(r_length)
 
         tau_combined = (obs1.e_tauint[e_name] + obs2.e_tauint[e_name]) / 2
-        dvalue += gamma * (1 + 1 / e_N) / e_N * 2 * tau_combined
+        dvalue += gamma / e_N * (1 + 1 / e_N) / e_N * 2 * tau_combined
 
     if np.abs(dvalue / obs1.dvalue / obs2.dvalue) > 1.0:
         dvalue = np.sign(dvalue) * obs1.dvalue * obs2.dvalue