diff --git a/openmc/deplete/operator.py b/openmc/deplete/operator.py
index ffbffbc73..21c96b047 100644
--- a/openmc/deplete/operator.py
+++ b/openmc/deplete/operator.py
@@ -525,7 +525,8 @@ class Operator(TransportOperator):
         rates = self.reaction_rates
         rates[:, :, :] = 0.0
 
-        k_combined = openmc.capi.keff()[0]
+        # Get k and uncertainty
+        k_combined = openmc.capi.keff()
 
         # Extract tally bins
         materials = self.burnable_mats
diff --git a/openmc/deplete/results.py b/openmc/deplete/results.py
index 6170a4464..b0dc4f3bc 100644
--- a/openmc/deplete/results.py
+++ b/openmc/deplete/results.py
@@ -237,8 +237,8 @@ class Results(object):
                               chunks=(1, 1, n_mats, n_nuc_rxn, n_rxn),
                               dtype='float64')
 
-        handle.create_dataset("eigenvalues", (1, n_stages),
-                              maxshape=(None, n_stages), dtype='float64')
+        handle.create_dataset("eigenvalues", (1, n_stages, 2),
+                              maxshape=(None, n_stages, 2), dtype='float64')
 
         handle.create_dataset("time", (1, 2), maxshape=(None, 2), dtype='float64')
 
diff --git a/openmc/deplete/results_list.py b/openmc/deplete/results_list.py
index 9fb6eec86..26570704e 100644
--- a/openmc/deplete/results_list.py
+++ b/openmc/deplete/results_list.py
@@ -95,7 +95,7 @@ class ResultsList(list):
 
         """
         time = np.empty_like(self, dtype=float)
-        eigenvalue = np.empty_like(self, dtype=float)
+        eigenvalue = np.empty((len(self), 2), dtype=float)
 
         # Get time/eigenvalue at each point
         for i, result in enumerate(self):