diff --git a/include/openmc/capi.h b/include/openmc/capi.h
index 43c33dd91a..f08ec5c02f 100644
--- a/include/openmc/capi.h
+++ b/include/openmc/capi.h
@@ -145,13 +145,13 @@ extern "C" {
   //! \param[in] meshtyally_id id of CMFD Mesh Tally
   //! \param[in] cmfd_indices indices storing spatial and energy dimensions of CMFD problem
   //! \param[in] norm CMFD normalization factor
-  extern "C" void openmc_initialize_mesh_egrid(const int meshtally_id, const int* cmfd_indices,
-                                               const double norm);
+  void openmc_initialize_mesh_egrid(const int meshtally_id, const int* cmfd_indices,
+                                    const double norm);
 
   //! Sets the mesh and energy grid for CMFD reweight
   //! \param[in] feedback whether or not to run CMFD feedback
   //! \param[in] cmfd_src computed CMFD source
-  extern "C" void openmc_cmfd_reweight(const bool feedback, const double* cmfd_src);
+  void openmc_cmfd_reweight(const bool feedback, const double* cmfd_src);
 
   //! Sets the fixed variables that are used for CMFD linear solver
   //! \param[in] indptr CSR format index pointer array of loss matrix
@@ -162,10 +162,10 @@ extern "C" {
   //! \param[in] spectral spectral radius of CMFD matrices and tolerances
   //! \param[in] map coremap for problem, storing accelerated regions
   //! \param[in] use_all_threads whether to use all threads when running CMFD solver
-  extern "C" void openmc_initialize_linsolver(const int* indptr, int len_indptr,
-                                              const int* indices, int n_elements,
-                                              int dim, double spectral,
-                                              const int* map, bool use_all_threads);
+  void openmc_initialize_linsolver(const int* indptr, int len_indptr,
+                                   const int* indices, int n_elements,
+                                   int dim, double spectral,
+                                   const int* map, bool use_all_threads);
 
   //! Runs a Gauss Seidel linear solver to solve CMFD matrix equations
   //! linear solver
@@ -174,9 +174,19 @@ extern "C" {
   //! \param[out] x unknown vector
   //! \param[in] tol tolerance on final error
   //! \return number of inner iterations required to reach convergence
-  extern "C" int openmc_run_linsolver(const double* A_data, const double* b,
+  int openmc_run_linsolver(const double* A_data, const double* b,
                                       double* x, double tol);
 
+  //! Export physical properties for model
+  //! \param[in] filename Filename to write to
+  //! \return Error code
+  int openmc_properties_export(const char* filename);
+
+  //! Import physical properties for model
+  //! \param[in] filename Filename to read from
+  // \return Error code
+  int openmc_properties_import(const char* filename);
+
   // Error codes
   extern int OPENMC_E_UNASSIGNED;
   extern int OPENMC_E_ALLOCATE;
diff --git a/include/openmc/summary.h b/include/openmc/summary.h
index 95fb0be167..ff2ab71a89 100644
--- a/include/openmc/summary.h
+++ b/include/openmc/summary.h
@@ -11,16 +11,6 @@ void write_nuclides(hid_t file);
 void write_geometry(hid_t file);
 void write_materials(hid_t file);
 
-//! Export physical properties for model
-//! \param[in] filename Filename to write to
-//! \return Error code
-extern "C" int openmc_properties_export(const char* filename);
-
-//! Import physical properties for model
-//! \param[in] filename Filename to read from
-// \return Error code
-extern "C" int openmc_properties_import(const char* filename);
-
 }
 
 #endif // OPENMC_SUMMARY_H
diff --git a/src/summary.cpp b/src/summary.cpp
index 29d37009b1..c2276c063e 100644
--- a/src/summary.cpp
+++ b/src/summary.cpp
@@ -2,6 +2,7 @@
 
 #include <fmt/core.h>
 
+#include "openmc/capi.h"
 #include "openmc/cell.h"
 #include "openmc/file_utils.h"
 #include "openmc/hdf5_interface.h"
@@ -136,6 +137,10 @@ void write_materials(hid_t file)
   close_group(materials_group);
 }
 
+//==============================================================================
+// C API
+//==============================================================================
+
 extern "C" int openmc_properties_export(const char* filename)
 {
   // Set a default filename if none was passed