diff --git a/pyerrors/correlators.py b/pyerrors/correlators.py
index 3c1b8a75..233c7499 100644
--- a/pyerrors/correlators.py
+++ b/pyerrors/correlators.py
@@ -266,9 +266,11 @@ class Corr:
         symmetric_corr = self.matrix_symmetric()
         if sorted_list is None:
             if (ts is None):
-                raise Exception("ts is required if sorted_list=None")
+                raise Exception("ts is required if sorted_list=None.")
+            if (ts <= t0):
+                raise Exception("ts has to be larger than t0.")
             if (self.content[t0] is None) or (self.content[ts] is None):
-                raise Exception("Corr not defined at t0/ts")
+                raise Exception("Corr not defined at t0/ts.")
             G0, Gt = np.empty([self.N, self.N], dtype="double"), np.empty([self.N, self.N], dtype="double")
             for i in range(self.N):
                 for j in range(self.N):
@@ -281,8 +283,8 @@ class Corr:
         elif sorted_list in ["Eigenvalue", "Eigenvector"]:
             if sorted_list == "Eigenvalue" and ts is not None:
                 warnings.warn("ts has no effect when sorting by eigenvalue is chosen.", RuntimeWarning)
-            all_vecs = []
-            for t in range(self.T):
+            all_vecs = [None] * (t0 + 1)
+            for t in range(t0 + 1, self.T):
                 try:
                     G0, Gt = np.empty([self.N, self.N], dtype="double"), np.empty([self.N, self.N], dtype="double")
                     for i in range(self.N):
@@ -302,7 +304,7 @@ class Corr:
                 if (ts is None):
                     raise Exception("ts is required for the Eigenvector sorting method.")
                 all_vecs = _sort_vectors(all_vecs, ts)
-                all_vecs = [a[state] for a in all_vecs]
+                all_vecs = [a[state] if a is not None else None for a in all_vecs]
         else:
             raise Exception("Unkown value for 'sorted_list'.")
 
diff --git a/tests/correlators_test.py b/tests/correlators_test.py
index 03f8eea3..5242339f 100644
--- a/tests/correlators_test.py
+++ b/tests/correlators_test.py
@@ -230,8 +230,8 @@ def test_matrix_corr():
     corr_mat = pe.Corr(np.array([[corr_aa, corr_ab], [corr_ab, corr_aa]]))
     corr_mat.item(0, 0)
 
-    vec_0 = corr_mat.GEVP(0, 0, sorted_list=None)
-    vec_1 = corr_mat.GEVP(0, 0, state=1, sorted_list=None)
+    vec_0 = corr_mat.GEVP(0, 1, sorted_list=None)
+    vec_1 = corr_mat.GEVP(0, 1, state=1, sorted_list=None)
 
     corr_0 = corr_mat.projected(vec_0)
     corr_1 = corr_mat.projected(vec_1)
@@ -240,7 +240,7 @@ def test_matrix_corr():
     assert np.all([o == 0 for o in corr_1 - corr_aa])
 
     corr_mat.GEVP(0, sorted_list="Eigenvalue")
-    corr_mat.GEVP(0, 0, sorted_list="Eigenvector")
+    corr_mat.GEVP(0, 1, sorted_list="Eigenvector")
 
     corr_mat.matrix_symmetric()