diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1797ae5d3..81c16aa48 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -447,7 +447,9 @@ set(LIBOPENMC_CXX_SRC
   src/pugixml/pugixml.hpp)
 add_library(libopenmc SHARED ${LIBOPENMC_FORTRAN_SRC} ${LIBOPENMC_CXX_SRC})
 set_target_properties(libopenmc PROPERTIES OUTPUT_NAME openmc)
-add_executable(${program} src/main.F90)
+
+add_executable(${program} src/main.cpp)
+target_include_directories(${program} PUBLIC include)
 
 #===============================================================================
 # Add compiler/linker flags
@@ -460,7 +462,7 @@ target_include_directories(libopenmc PUBLIC ${HDF5_INCLUDE_DIRS})
 
 # The executable and the faddeeva package use only one language.  They can be
 # set via target_compile_options which accepts a list.
-target_compile_options(${program} PUBLIC ${f90flags})
+target_compile_options(${program} PUBLIC ${cxxflags})
 target_compile_options(faddeeva PRIVATE ${cflags})
 
 # The libopenmc library has both F90 and C++ so the compile flags must be set
diff --git a/include/openmc.h b/include/openmc.h
index ed3a86054..194545345 100644
--- a/include/openmc.h
+++ b/include/openmc.h
@@ -70,6 +70,7 @@ extern "C" {
   int openmc_meshsurface_filter_set_mesh(int32_t index, int32_t index_mesh);
   int openmc_next_batch(int* status);
   int openmc_nuclide_name(int index, char** name);
+  int openmc_particle_restart();
   void openmc_plot_geometry();
   void openmc_reset();
   int openmc_run();
@@ -122,8 +123,9 @@ extern "C" {
 
   // Global variables
   extern char openmc_err_msg[256];
-  extern double keff;
-  extern double keff_std;
+  extern double openmc_keff;
+  extern double openmc_keff_std;
+  extern bool openmc_master;
   extern int32_t n_batches;
   extern int32_t n_cells;
   extern int32_t n_filters;
@@ -139,9 +141,16 @@ extern "C" {
   extern int32_t n_surfaces;
   extern int32_t n_tallies;
   extern int32_t n_universes;
-  extern int run_mode;
-  extern bool simulation_initialized;
-  extern int verbosity;
+  extern int openmc_run_mode;
+  extern bool openmc_simulation_initialized;
+  extern int openmc_verbosity;
+
+  // Run modes
+  constexpr int RUN_MODE_FIXEDSOURCE {1};
+  constexpr int RUN_MODE_EIGENVALUE {2};
+  constexpr int RUN_MODE_PLOTTING {3};
+  constexpr int RUN_MODE_PARTICLE {4};
+  constexpr int RUN_MODE_VOLUME {5};
 
 #ifdef __cplusplus
 }
diff --git a/openmc/capi/core.py b/openmc/capi/core.py
index f80b5fe54..d35690503 100644
--- a/openmc/capi/core.py
+++ b/openmc/capi/core.py
@@ -178,8 +178,9 @@ def keff():
         return tuple(k)
     else:
         # Otherwise, return the tracklength estimator
-        mean = c_double.in_dll(_dll, 'keff').value
-        std_dev = c_double.in_dll(_dll, 'keff_std').value if n > 1 else np.inf
+        mean = c_double.in_dll(_dll, 'openmc_keff').value
+        std_dev = c_double.in_dll(_dll, 'openmc_keff_std').value \
+                  if n > 1 else np.inf
         return (mean, std_dev)
 
 
diff --git a/openmc/capi/settings.py b/openmc/capi/settings.py
index 1063d6463..d706112c4 100644
--- a/openmc/capi/settings.py
+++ b/openmc/capi/settings.py
@@ -20,11 +20,11 @@ class _Settings(object):
     generations_per_batch = _DLLGlobal(c_int32, 'gen_per_batch')
     inactive = _DLLGlobal(c_int32, 'n_inactive')
     particles = _DLLGlobal(c_int64, 'n_particles')
-    verbosity = _DLLGlobal(c_int, 'verbosity')
+    verbosity = _DLLGlobal(c_int, 'openmc_verbosity')
 
     @property
     def run_mode(self):
-        i = c_int.in_dll(_dll, 'run_mode').value
+        i = c_int.in_dll(_dll, 'openmc_run_mode').value
         try:
             return _RUN_MODES[i]
         except KeyError:
@@ -32,7 +32,7 @@ class _Settings(object):
 
     @run_mode.setter
     def run_mode(self, mode):
-        current_idx = c_int.in_dll(_dll, 'run_mode')
+        current_idx = c_int.in_dll(_dll, 'openmc_run_mode')
         for idx, mode_value in _RUN_MODES.items():
             if mode_value == mode:
                 current_idx.value = idx
diff --git a/src/main.F90 b/src/main.F90
deleted file mode 100644
index 372e993f5..000000000
--- a/src/main.F90
+++ /dev/null
@@ -1,51 +0,0 @@
-program main
-
-  use, intrinsic :: ISO_C_BINDING
-
-  use constants
-  use message_passing
-  use openmc_api, only: openmc_init, openmc_finalize, openmc_run, &
-                        openmc_plot_geometry, openmc_calculate_volumes
-  use particle_restart, only: run_particle_restart
-  use settings, only: run_mode
-
-  implicit none
-
-  integer(C_INT) :: err
-#ifdef OPENMC_MPI
-  integer :: mpi_err ! MPI error code
-#endif
-
-  ! Initialize run -- when run with MPI, pass communicator
-#ifdef OPENMC_MPI
-#ifdef OPENMC_MPIF08
-  call openmc_init(MPI_COMM_WORLD % MPI_VAL)
-#else
-  call openmc_init(MPI_COMM_WORLD)
-#endif
-#else
-  call openmc_init()
-#endif
-
-  ! start problem based on mode
-  select case (run_mode)
-  case (MODE_FIXEDSOURCE, MODE_EIGENVALUE)
-    err = openmc_run()
-  case (MODE_PLOTTING)
-    call openmc_plot_geometry()
-  case (MODE_PARTICLE)
-    if (master) call run_particle_restart()
-  case (MODE_VOLUME)
-    call openmc_calculate_volumes()
-  end select
-
-  ! finalize run
-  call openmc_finalize()
-
-#ifdef OPENMC_MPI
-  ! If MPI is in use and enabled, terminate it
-  call MPI_FINALIZE(mpi_err)
-#endif
-
-
-end program main
diff --git a/src/main.cpp b/src/main.cpp
new file mode 100644
index 000000000..7b2ccb5c3
--- /dev/null
+++ b/src/main.cpp
@@ -0,0 +1,40 @@
+#include "openmc.h"
+
+#ifdef MPI
+#include <mpi.h>
+#else
+#define MPI_COMM_WORLD nullptr
+#endif
+
+
+int main(int argc, char** argv) {
+  int err;
+
+  // Initialize run -- when run with MPI, pass communicator
+  openmc_init(MPI_COMM_WORLD);
+
+  // start problem based on mode
+  switch (openmc_run_mode) {
+  case RUN_MODE_FIXEDSOURCE:
+  case RUN_MODE_EIGENVALUE:
+    err = openmc_run();
+    break;
+  case RUN_MODE_PLOTTING:
+    openmc_plot_geometry();
+    break;
+  case RUN_MODE_PARTICLE:
+    if (openmc_master) err = openmc_particle_restart();
+    break;
+  case RUN_MODE_VOLUME:
+    openmc_calculate_volumes();
+    break;
+  }
+
+  // Finalize and free up memory
+  openmc_finalize();
+
+  // If MPI is in use and enabled, terminate it
+#ifdef MPI
+  err = MPI_Finalize();
+#endif
+}
diff --git a/src/message_passing.F90 b/src/message_passing.F90
index 7391a632c..f9a16ee75 100644
--- a/src/message_passing.F90
+++ b/src/message_passing.F90
@@ -1,5 +1,7 @@
 module message_passing
 
+  use, intrinsic :: ISO_C_BINDING
+
 #ifdef OPENMC_MPI
 #ifdef OPENMC_MPIF08
   use mpi_f08
@@ -14,7 +16,7 @@ module message_passing
 
   integer :: n_procs     = 1       ! number of processes
   integer :: rank        = 0       ! rank of process
-  logical :: master      = .true.  ! master process?
+  logical(C_BOOL), bind(C, name='openmc_master') :: master  = .true.  ! master process?
   logical :: mpi_enabled = .false. ! is MPI in use and initialized?
 #ifdef OPENMC_MPIF08
   type(MPI_Datatype) :: MPI_BANK   ! MPI datatype for fission bank
diff --git a/src/nuclide_header.F90 b/src/nuclide_header.F90
index 8362f5d41..76fc26a74 100644
--- a/src/nuclide_header.F90
+++ b/src/nuclide_header.F90
@@ -277,7 +277,7 @@ contains
     integer,          intent(inout) :: method
     real(8),          intent(in)    :: tolerance
     real(8),          intent(in)    :: minmax(2)  ! range of temperatures
-    logical,          intent(in)    :: master     ! if this is the master proc
+    logical(C_BOOL),  intent(in)    :: master     ! if this is the master proc
     integer,          intent(in)    :: i_nuclide  ! Nuclide index in nuclides
 
     integer :: i
diff --git a/src/particle_restart.F90 b/src/particle_restart.F90
index 2d15f2ddc..fc8a05277 100644
--- a/src/particle_restart.F90
+++ b/src/particle_restart.F90
@@ -20,20 +20,23 @@ module particle_restart
 
   implicit none
   private
-  public ::  run_particle_restart
+  public ::  openmc_particle_restart
 
 contains
 
 !===============================================================================
-! RUN_PARTICLE_RESTART is the main routine that runs the particle restart
+! OPENMC_PARTICLE_RESTART is the main routine that runs the particle restart
 !===============================================================================
 
-  subroutine run_particle_restart()
+  function openmc_particle_restart() result(err) bind(C)
+    integer(C_INT) :: err
 
     integer(8) :: particle_seed
     integer :: previous_run_mode
     type(Particle) :: p
 
+    err = 0
+
     ! Set verbosity high
     verbosity = 10
 
@@ -66,7 +69,7 @@ contains
 
     deallocate(micro_xs)
 
-  end subroutine run_particle_restart
+  end function openmc_particle_restart
 
 !===============================================================================
 ! READ_PARTICLE_RESTART reads the particle restart file
diff --git a/src/settings.F90 b/src/settings.F90
index 83aebce86..4de72e8c4 100644
--- a/src/settings.F90
+++ b/src/settings.F90
@@ -75,14 +75,14 @@ module settings
   real(8) :: weight_survive = ONE
 
   ! Mode to run in (fixed source, eigenvalue, plotting, etc)
-  integer(C_INT), bind(C) :: run_mode = NONE
+  integer(C_INT), bind(C, name='openmc_run_mode') :: run_mode = NONE
 
   ! Restart run
   logical :: restart_run = .false.
 
   ! The verbosity controls how much information will be printed to the screen
   ! and in logs
-  integer(C_INT), bind(C) :: verbosity = 7
+  integer(C_INT), bind(C, name='openmc_verbosity') :: verbosity = 7
 
   logical :: check_overlaps = .false.
 
diff --git a/src/simulation_header.F90 b/src/simulation_header.F90
index 11be9bf9c..67bf3062b 100644
--- a/src/simulation_header.F90
+++ b/src/simulation_header.F90
@@ -23,7 +23,8 @@ module simulation_header
   integer :: current_batch     ! current batch
   integer :: current_gen       ! current generation within a batch
   integer :: total_gen     = 0 ! total number of generations simulated
-  logical(C_BOOL), bind(C) :: simulation_initialized = .false.
+  logical(C_BOOL), bind(C, name='openmc_simulation_initialized') :: &
+       simulation_initialized = .false.
   logical :: need_depletion_rx ! need to calculate depletion reaction rx?
 
   ! ============================================================================
@@ -40,8 +41,8 @@ module simulation_header
 
   ! Temporary k-effective values
   type(VectorReal) :: k_generation ! single-generation estimates of k
-  real(C_DOUBLE), bind(C) :: keff = ONE  ! average k over active batches
-  real(C_DOUBLE), bind(C) :: keff_std    ! standard deviation of average k
+  real(C_DOUBLE), bind(C, name='openmc_keff')     :: keff = ONE  ! average k over active batches
+  real(C_DOUBLE), bind(C, name='openmc_keff_std') :: keff_std    ! standard deviation of average k
   real(8) :: k_col_abs = ZERO ! sum over batches of k_collision * k_absorption
   real(8) :: k_col_tra = ZERO ! sum over batches of k_collision * k_tracklength
   real(8) :: k_abs_tra = ZERO ! sum over batches of k_absorption * k_tracklength