diff --git a/src/input_xml.F90 b/src/input_xml.F90
index 0718fc589..d86afd3cf 100644
--- a/src/input_xml.F90
+++ b/src/input_xml.F90
@@ -221,11 +221,6 @@ contains
     ! Get proper XMLNode type given pointer
     root % ptr = root_ptr
 
-    if (run_mode == MODE_EIGENVALUE) then
-      ! Preallocate space for keff and entropy by generation
-      call k_generation_reserve(n_max_batches*gen_per_batch)
-    end if
-
     ! Particle tracks
     if (check_for_node(root, "track")) then
       ! Make sure that there are three values per particle
diff --git a/src/settings.cpp b/src/settings.cpp
index bf97e44b8..556fbd24d 100644
--- a/src/settings.cpp
+++ b/src/settings.cpp
@@ -12,6 +12,7 @@
 #include "openmc/distribution.h"
 #include "openmc/distribution_multi.h"
 #include "openmc/distribution_spatial.h"
+#include "openmc/eigenvalue.h"
 #include "openmc/error.h"
 #include "openmc/file_utils.h"
 #include "openmc/mesh.h"
@@ -141,7 +142,10 @@ void get_run_parameters(pugi::xml_node node_base)
       gen_per_batch = std::stoi(get_node_value(node_base, "generations_per_batch"));
     }
 
-    // TODO: Preallocate space for keff and entropy by generation
+    // Preallocate space for keff and entropy by generation
+    int m = settings::n_max_batches * settings::gen_per_batch;
+    simulation::k_generation.reserve(m);
+    entropy.reserve(m);
 
     // Get the trigger information for keff
     if (check_for_node(node_base, "keff_trigger")) {
diff --git a/src/simulation_header.F90 b/src/simulation_header.F90
index 288a8422c..e16b93432 100644
--- a/src/simulation_header.F90
+++ b/src/simulation_header.F90
@@ -84,11 +84,6 @@ module simulation_header
     subroutine k_generation_clear() bind(C)
     end subroutine
 
-    subroutine k_generation_reserve(i) bind(C)
-      import C_INT
-      integer(C_INT), value :: i
-    end subroutine
-
     function work_index(rank) result(i) bind(C)
       import C_INT, C_INT64_T
       integer(C_INT), value :: rank