diff --git a/include/openmc/cell.h b/include/openmc/cell.h
index 5efbdd99e..5cd819c26 100644
--- a/include/openmc/cell.h
+++ b/include/openmc/cell.h
@@ -49,11 +49,11 @@ class Universe;
 class UniversePartitioner;
 
 namespace model {
-  extern std::vector<std::unique_ptr<Cell>> cells;
   extern std::unordered_map<int32_t, int32_t> cell_map;
+  extern std::vector<std::unique_ptr<Cell>> cells;
 
-  extern std::vector<std::unique_ptr<Universe>> universes;
   extern std::unordered_map<int32_t, int32_t> universe_map;
+  extern std::vector<std::unique_ptr<Universe>> universes;
 } // namespace model
 
 //==============================================================================
diff --git a/include/openmc/cross_sections.h b/include/openmc/cross_sections.h
index 3700bc217..3afcf6b17 100644
--- a/include/openmc/cross_sections.h
+++ b/include/openmc/cross_sections.h
@@ -43,12 +43,12 @@ using LibraryKey = std::pair<Library::Type, std::string>;
 
 namespace data {
 
-//!< Data libraries
-extern std::vector<Library> libraries;
-
 //! Maps (type, name) to index in libraries
 extern std::map<LibraryKey, std::size_t> library_map;
 
+//!< Data libraries
+extern std::vector<Library> libraries;
+
 } // namespace data
 
 //==============================================================================
diff --git a/include/openmc/lattice.h b/include/openmc/lattice.h
index bf18d92e4..618859c80 100644
--- a/include/openmc/lattice.h
+++ b/include/openmc/lattice.h
@@ -35,8 +35,8 @@ enum class LatticeType {
 class Lattice;
 
 namespace model {
-  extern std::vector<std::unique_ptr<Lattice>> lattices;
   extern std::unordered_map<int32_t, int32_t> lattice_map;
+  extern std::vector<std::unique_ptr<Lattice>> lattices;
 } // namespace model
 
 //==============================================================================
diff --git a/include/openmc/mesh.h b/include/openmc/mesh.h
index a7160b0c8..eed36c7f8 100644
--- a/include/openmc/mesh.h
+++ b/include/openmc/mesh.h
@@ -32,8 +32,8 @@ class Mesh;
 
 namespace model {
 
-extern std::vector<std::unique_ptr<Mesh>> meshes;
 extern std::unordered_map<int32_t, int32_t> mesh_map;
+extern std::vector<std::unique_ptr<Mesh>> meshes;
 
 } // namespace model
 
diff --git a/include/openmc/nuclide.h b/include/openmc/nuclide.h
index 3ea3a05a7..e3f7c3d74 100644
--- a/include/openmc/nuclide.h
+++ b/include/openmc/nuclide.h
@@ -138,8 +138,8 @@ extern double temperature_min;
 //! Maximum temperature in [K] that nuclide data is available at
 extern double temperature_max;
 
-extern std::vector<std::unique_ptr<Nuclide>> nuclides;
 extern std::unordered_map<std::string, int> nuclide_map;
+extern std::vector<std::unique_ptr<Nuclide>> nuclides;
 
 } // namespace data
 
diff --git a/include/openmc/plot.h b/include/openmc/plot.h
index 2468af1bf..76fc462c3 100644
--- a/include/openmc/plot.h
+++ b/include/openmc/plot.h
@@ -27,8 +27,8 @@ class Plot;
 
 namespace model {
 
-extern std::vector<Plot> plots; //!< Plot instance container
 extern std::unordered_map<int, int> plot_map; //!< map of plot ids to index
+extern std::vector<Plot> plots; //!< Plot instance container
 
 extern uint64_t plotter_prn_seeds[N_STREAMS]; // Random number seeds used for plotter
 extern int plotter_stream; // Stream index used by the plotter
diff --git a/include/openmc/surface.h b/include/openmc/surface.h
index 784ecbcec..cef5f4f88 100644
--- a/include/openmc/surface.h
+++ b/include/openmc/surface.h
@@ -24,8 +24,8 @@ namespace openmc {
 class Surface;
 
 namespace model {
-  extern std::vector<std::unique_ptr<Surface>> surfaces;
   extern std::unordered_map<int, int> surface_map;
+  extern std::vector<std::unique_ptr<Surface>> surfaces;
 } // namespace model
 
 //==============================================================================
diff --git a/include/openmc/tallies/derivative.h b/include/openmc/tallies/derivative.h
index 421094c99..53e6925ba 100644
--- a/include/openmc/tallies/derivative.h
+++ b/include/openmc/tallies/derivative.h
@@ -70,8 +70,8 @@ void score_track_derivative(Particle& p, double distance);
 namespace openmc {
 
 namespace model {
-extern std::vector<TallyDerivative> tally_derivs;
 extern std::unordered_map<int, int> tally_deriv_map;
+extern std::vector<TallyDerivative> tally_derivs;
 } // namespace model
 
 } // namespace openmc
diff --git a/include/openmc/thermal.h b/include/openmc/thermal.h
index ca2f78562..a18658fe3 100644
--- a/include/openmc/thermal.h
+++ b/include/openmc/thermal.h
@@ -23,8 +23,8 @@ namespace openmc {
 class ThermalScattering;
 
 namespace data {
-extern std::vector<std::unique_ptr<ThermalScattering>> thermal_scatt;
 extern std::unordered_map<std::string, int> thermal_scatt_map;
+extern std::vector<std::unique_ptr<ThermalScattering>> thermal_scatt;
 }
 
 //==============================================================================
diff --git a/src/cell.cpp b/src/cell.cpp
index fd488f360..6c2bbf6bd 100644
--- a/src/cell.cpp
+++ b/src/cell.cpp
@@ -32,11 +32,11 @@ namespace openmc {
 //==============================================================================
 
 namespace model {
-  std::vector<std::unique_ptr<Cell>> cells;
   std::unordered_map<int32_t, int32_t> cell_map;
+  std::vector<std::unique_ptr<Cell>> cells;
 
-  std::vector<std::unique_ptr<Universe>> universes;
   std::unordered_map<int32_t, int32_t> universe_map;
+  std::vector<std::unique_ptr<Universe>> universes;
 } // namespace model
 
 //==============================================================================
diff --git a/src/cross_sections.cpp b/src/cross_sections.cpp
index 6267dc5f9..c06a11924 100644
--- a/src/cross_sections.cpp
+++ b/src/cross_sections.cpp
@@ -34,8 +34,8 @@ namespace openmc {
 
 namespace data {
 
-std::vector<Library> libraries;
 std::map<LibraryKey, std::size_t> library_map;
+std::vector<Library> libraries;
 
 }
 
diff --git a/src/lattice.cpp b/src/lattice.cpp
index f0c3dc979..18b40dff4 100644
--- a/src/lattice.cpp
+++ b/src/lattice.cpp
@@ -22,8 +22,8 @@ namespace openmc {
 //==============================================================================
 
 namespace model {
-  std::vector<std::unique_ptr<Lattice>> lattices;
   std::unordered_map<int32_t, int32_t> lattice_map;
+  std::vector<std::unique_ptr<Lattice>> lattices;
 }
 
 //==============================================================================
diff --git a/src/mesh.cpp b/src/mesh.cpp
index b76be1ee8..4954ca373 100644
--- a/src/mesh.cpp
+++ b/src/mesh.cpp
@@ -35,8 +35,8 @@ namespace openmc {
 
 namespace model {
 
-std::vector<std::unique_ptr<Mesh>> meshes;
 std::unordered_map<int32_t, int32_t> mesh_map;
+std::vector<std::unique_ptr<Mesh>> meshes;
 
 } // namespace model
 
diff --git a/src/nuclide.cpp b/src/nuclide.cpp
index 9b4500e63..59e5f6e8c 100644
--- a/src/nuclide.cpp
+++ b/src/nuclide.cpp
@@ -32,8 +32,8 @@ std::array<double, 2> energy_min {0.0, 0.0};
 std::array<double, 2> energy_max {INFTY, INFTY};
 double temperature_min {0.0};
 double temperature_max {INFTY};
-std::vector<std::unique_ptr<Nuclide>> nuclides;
 std::unordered_map<std::string, int> nuclide_map;
+std::vector<std::unique_ptr<Nuclide>> nuclides;
 } // namespace data
 
 //==============================================================================
diff --git a/src/plot.cpp b/src/plot.cpp
index bc94b3ad6..e2fe5abde 100644
--- a/src/plot.cpp
+++ b/src/plot.cpp
@@ -80,8 +80,8 @@ void PropertyData::set_overlap(size_t y, size_t x) {
 
 namespace model {
 
-std::vector<Plot> plots;
 std::unordered_map<int, int> plot_map;
+std::vector<Plot> plots;
 uint64_t plotter_seed = 1;
 
 } // namespace model
diff --git a/src/surface.cpp b/src/surface.cpp
index 8133a6a7e..f5a7f9f5f 100644
--- a/src/surface.cpp
+++ b/src/surface.cpp
@@ -23,8 +23,8 @@ namespace openmc {
 //==============================================================================
 
 namespace model {
-  std::vector<std::unique_ptr<Surface>> surfaces;
   std::unordered_map<int, int> surface_map;
+  std::vector<std::unique_ptr<Surface>> surfaces;
 } // namespace model
 
 //==============================================================================
diff --git a/src/tallies/derivative.cpp b/src/tallies/derivative.cpp
index 6c802d856..fecfa3f1c 100644
--- a/src/tallies/derivative.cpp
+++ b/src/tallies/derivative.cpp
@@ -18,8 +18,8 @@ namespace openmc {
 //==============================================================================
 
 namespace model {
-  std::vector<TallyDerivative> tally_derivs;
   std::unordered_map<int, int> tally_deriv_map;
+  std::vector<TallyDerivative> tally_derivs;
 }
 
 //==============================================================================
diff --git a/src/thermal.cpp b/src/thermal.cpp
index 352ca8dd3..f8e9b280b 100644
--- a/src/thermal.cpp
+++ b/src/thermal.cpp
@@ -27,8 +27,8 @@ namespace openmc {
 //==============================================================================
 
 namespace data {
-std::vector<std::unique_ptr<ThermalScattering>> thermal_scatt;
 std::unordered_map<std::string, int> thermal_scatt_map;
+std::vector<std::unique_ptr<ThermalScattering>> thermal_scatt;
 }
 
 //==============================================================================