diff --git a/pyerrors/covobs.py b/pyerrors/covobs.py
index b0eb4efb..64d90150 100644
--- a/pyerrors/covobs.py
+++ b/pyerrors/covobs.py
@@ -23,6 +23,7 @@ class Covobs:
         self.cov = np.array(cov)
         if self.cov.ndim == 0:
             self.N = 1
+            self.cov = np.diag([self.cov])
         elif self.cov.ndim == 1:
             self.N = len(self.cov)
             self.cov = np.diag(self.cov)
@@ -48,6 +49,8 @@ class Covobs:
             self.grad[pos] = 1.
         else:
             self.grad = np.array(grad)
+            if self.grad.ndim == 1:
+                self.grad = np.reshape(self.grad, (self.N, 1))
         self.value = mean
 
     def errsq(self):
diff --git a/pyerrors/obs.py b/pyerrors/obs.py
index bea4f7e0..934b2518 100644
--- a/pyerrors/obs.py
+++ b/pyerrors/obs.py
@@ -1069,7 +1069,7 @@ def derived_observable(func, data, array_mode=False, **kwargs):
     for o in raveled_data:
         for name in o.cov_names:
             if name in allcov:
-                if not np.array_equal(allcov[name], o.covobs[name].cov):
+                if not np.allclose(allcov[name], o.covobs[name].cov, rtol=1e-14, atol=1e-14):
                     raise Exception('Inconsistent covariance matrices for %s!' % (name))
             else:
                 allcov[name] = o.covobs[name].cov