diff --git a/docs/source/io_formats/settings.rst b/docs/source/io_formats/settings.rst
index 09d7db1236..588b58b478 100644
--- a/docs/source/io_formats/settings.rst
+++ b/docs/source/io_formats/settings.rst
@@ -465,7 +465,7 @@ attributes/sub-elements:
     as complex as is required to define the source for your problem. The library
     has a few basic requirements:
 
-    * It must contain a class that inherits from ``openmc::CustomSource``;
+    * It must contain a class that inherits from ``openmc::Source``;
     * The class must implement a function called ``sample()``;
     * There must be an ``openmc_create_source()`` function that creates the source
       as a unique pointer. This function can be used to pass parameters through to
diff --git a/docs/source/usersguide/settings.rst b/docs/source/usersguide/settings.rst
index 340d4af00c..df22328e3a 100644
--- a/docs/source/usersguide/settings.rst
+++ b/docs/source/usersguide/settings.rst
@@ -194,9 +194,9 @@ below.
   #include "openmc/source.h"
   #include "openmc/particle.h"
 
-  class Source : public openmc::CustomSource
+  class CustomSource : public openmc::Source
   {
-    openmc::Particle::Bank sample(uint64_t* seed)
+    openmc::Particle::Bank sample(uint64_t* seed) const
     {
       openmc::Particle::Bank particle;
       // weight
@@ -216,16 +216,16 @@ below.
     }
   };
 
-  extern "C" std::unique_ptr<Source> openmc_create_source(std::string parameters)
+  extern "C" std::unique_ptr<CustomSource> openmc_create_source(std::string parameters)
   {
-    return std::make_unique<Source>();
+    return std::make_unique<CustomSource>();
   }
 
 The above source creates monodirectional 14.08 MeV neutrons that are distributed
 in a ring with a 3 cm radius. This routine is not particularly complex, but
 should serve as an example upon which to build more complicated sources.
 
-  .. note:: The source class must inherit from ``openmc::CustomSource`` and
+  .. note:: The source class must inherit from ``openmc::Source`` and
             implement a ``sample()`` function.
 
   .. note:: The ``openmc_create_source()`` function signature must be declared
@@ -266,12 +266,12 @@ the source class when it is created:
   #include "openmc/source.h"
   #include "openmc/particle.h"
 
-  class Source : public openmc::CustomSource {
+  class CustomSource : public openmc::Source {
   public:
-    Source(double energy) : energy_{energy} { }
+    CustomSource(double energy) : energy_{energy} { }
 
     // Samples from an instance of this class.
-    openmc::Particle::Bank sample(uint64_t* seed)
+    openmc::Particle::Bank sample(uint64_t* seed) const
     {
       openmc::Particle::Bank particle;
       // weight
@@ -293,9 +293,9 @@ the source class when it is created:
     double energy_;
   };
 
-  extern "C" std::unique_ptr<Source> openmc_create_source(std::string parameter) {
+  extern "C" std::unique_ptr<CustomSource> openmc_create_source(std::string parameter) {
     double energy = std::stod(parameter);
-    return std::make_unique<Source>(energy);
+    return std::make_unique<CustomSource>(energy);
   }
 
 As with the basic custom source functionality, the custom source library
diff --git a/examples/custom_source/source_ring.cpp b/examples/custom_source/source_ring.cpp
index bc8a8a7f8d..a752216dce 100644
--- a/examples/custom_source/source_ring.cpp
+++ b/examples/custom_source/source_ring.cpp
@@ -5,9 +5,9 @@
 #include "openmc/source.h"
 #include "openmc/particle.h"
 
-class Source : public openmc::CustomSource
+class RingSource : public openmc::Source
 {
-  openmc::Particle::Bank sample(uint64_t* seed)
+  openmc::Particle::Bank sample(uint64_t* seed) const
   {
     openmc::Particle::Bank particle;
     // wgt
@@ -30,7 +30,7 @@ class Source : public openmc::CustomSource
 // A function to create a unique pointer to an instance of this class when generated
 // via a plugin call using dlopen/dlsym.
 // You must have external C linkage here otherwise dlopen will not find the file
-extern "C" std::unique_ptr<Source> openmc_create_source(std::string parameters)
+extern "C" std::unique_ptr<RingSource> openmc_create_source(std::string parameters)
 {
-  return std::make_unique<Source>();
+  return std::make_unique<RingSource>();
 }
diff --git a/examples/parameterized_custom_source/parameterized_source_ring.cpp b/examples/parameterized_custom_source/parameterized_source_ring.cpp
index c88333e15b..9f913dfee3 100644
--- a/examples/parameterized_custom_source/parameterized_source_ring.cpp
+++ b/examples/parameterized_custom_source/parameterized_source_ring.cpp
@@ -6,14 +6,13 @@
 #include "openmc/source.h"
 #include "openmc/particle.h"
 
-class Source : public openmc::CustomSource
-{
+class RingSource : public openmc::Source {
   public:
-    Source(double radius, double energy) : radius_(radius), energy_(energy) { }
+    RingSource(double radius, double energy) : radius_(radius), energy_(energy) { }
 
     // Defines a function that can create a unique pointer to a new instance of this class
     // by extracting the parameters from the provided string.
-    static std::unique_ptr<Source> from_string(std::string parameters)
+    static std::unique_ptr<RingSource> from_string(std::string parameters)
     {
       std::unordered_map<std::string, std::string> parameter_mapping;
 
@@ -28,11 +27,11 @@ class Source : public openmc::CustomSource
 
       double radius = std::stod(parameter_mapping["radius"]);
       double energy = std::stod(parameter_mapping["energy"]);
-      return std::make_unique<Source>(radius, energy);
+      return std::make_unique<RingSource>(radius, energy);
     }
 
     // Samples from an instance of this class.
-    openmc::Particle::Bank sample(uint64_t* seed)
+    openmc::Particle::Bank sample(uint64_t* seed) const
     {
       openmc::Particle::Bank particle;
       // wgt
@@ -60,7 +59,7 @@ class Source : public openmc::CustomSource
 // A function to create a unique pointer to an instance of this class when generated
 // via a plugin call using dlopen/dlsym.
 // You must have external C linkage here otherwise dlopen will not find the file
-extern "C" std::unique_ptr<Source> openmc_create_source(std::string parameters)
+extern "C" std::unique_ptr<RingSource> openmc_create_source(std::string parameters)
 {
-  return Source::from_string(parameters);
+  return RingSource::from_string(parameters);
 }
diff --git a/include/openmc/settings.h b/include/openmc/settings.h
index 85ef1c71ea..74cbbc1328 100644
--- a/include/openmc/settings.h
+++ b/include/openmc/settings.h
@@ -59,8 +59,6 @@ extern std::string path_cross_sections;   //!< path to cross_sections.xml
 extern std::string path_input;            //!< directory where main .xml files resides
 extern std::string path_output;           //!< directory where output files are written
 extern std::string path_particle_restart; //!< path to a particle restart file
-extern std::string path_source;
-extern std::string path_source_library;   //!< path to the source shared object
 extern std::string path_sourcepoint;      //!< path to a source file
 extern "C" std::string path_statepoint;   //!< path to a statepoint file
 
diff --git a/include/openmc/source.h b/include/openmc/source.h
index 529cb1836e..12e8156992 100644
--- a/include/openmc/source.h
+++ b/include/openmc/source.h
@@ -19,32 +19,47 @@ namespace openmc {
 // Global variables
 //==============================================================================
 
-class SourceDistribution;
+class Source;
 
 namespace model {
 
-extern std::vector<SourceDistribution> external_sources;
+extern std::vector<std::unique_ptr<Source>> external_sources;
 
 } // namespace model
 
 //==============================================================================
-//! External source distribution
+//! Abstract source interface
 //==============================================================================
 
-class SourceDistribution {
+class Source {
+public:
+  virtual ~Source() = default;
+
+  // Methods that must be implemented
+  virtual Particle::Bank sample(uint64_t* seed) const = 0;
+
+  // Methods that can be overridden
+  virtual double strength() const { return 1.0; }
+};
+
+//==============================================================================
+//! Source composed of independent spatial, angle, and energy distributions
+//==============================================================================
+
+class IndependentSource : public Source {
 public:
   // Constructors
-  SourceDistribution(UPtrSpace space, UPtrAngle angle, UPtrDist energy);
-  explicit SourceDistribution(pugi::xml_node node);
+  IndependentSource(UPtrSpace space, UPtrAngle angle, UPtrDist energy);
+  explicit IndependentSource(pugi::xml_node node);
 
   //! Sample from the external source distribution
   //! \param[inout] seed Pseudorandom seed pointer
   //! \return Sampled site
-  Particle::Bank sample(uint64_t* seed) const;
+  Particle::Bank sample(uint64_t* seed) const override;
 
   // Properties
   Particle::Type particle_type() const { return particle_; }
-  double strength() const { return strength_; }
+  double strength() const override { return strength_; }
 
   // Make observing pointers available
   SpatialDistribution* space() const { return space_.get(); }
@@ -59,14 +74,45 @@ private:
   UPtrDist energy_; //!< Energy distribution
 };
 
-class CustomSource {
-  public:
-    virtual ~CustomSource() {}
+//==============================================================================
+//! Source composed of particles read from a file
+//==============================================================================
 
-    virtual Particle::Bank sample(uint64_t* seed) = 0;
+class FileSource : public Source {
+public:
+  // Constructors
+  explicit FileSource(std::string path);
+
+  // Methods
+  Particle::Bank sample(uint64_t* seed) const override;
+
+private:
+  std::vector<Particle::Bank> sites_; //!< Source sites from a file
 };
 
-typedef std::unique_ptr<CustomSource> create_custom_source_t(std::string parameters);
+//==============================================================================
+//! Wrapper for custom sources that manages opening/closing shared library
+//==============================================================================
+
+class CustomSourceWrapper : public Source {
+public:
+  // Constructors, destructors
+  CustomSourceWrapper(std::string path, std::string parameters);
+  ~CustomSourceWrapper();
+
+  // Defer implementation to custom source library
+  Particle::Bank sample(uint64_t* seed) const override
+  {
+    return custom_source_->sample(seed);
+  }
+
+  double strength() const override { return custom_source_->strength(); }
+private:
+  void* shared_library_; //!< library from dlopen
+  std::unique_ptr<Source> custom_source_;
+};
+
+typedef std::unique_ptr<Source> create_custom_source_t(std::string parameters);
 
 //==============================================================================
 // Functions
@@ -81,18 +127,6 @@ extern "C" void initialize_source();
 //! \return Sampled source site
 Particle::Bank sample_external_source(uint64_t* seed);
 
-//! Sample a site from custom source library
-Particle::Bank sample_custom_source_library(uint64_t* seed);
-
-//! Load custom source library
-void load_custom_source_library();
-
-//! Release custom source library
-void close_custom_source_library();
-
-//! Fill source bank at the end of a generation for dlopen based source simulation
-void fill_source_bank_custom_source();
-
 void free_memory_source();
 
 } // namespace openmc
diff --git a/include/openmc/state_point.h b/include/openmc/state_point.h
index 4a901ac2a2..c50ca355b8 100644
--- a/include/openmc/state_point.h
+++ b/include/openmc/state_point.h
@@ -2,17 +2,19 @@
 #define OPENMC_STATE_POINT_H
 
 #include <cstdint>
+#include <vector>
 
 #include "hdf5.h"
 
 #include "openmc/capi.h"
+#include "openmc/particle.h"
 
 namespace openmc {
 
 void load_state_point();
 void write_source_point(const char* filename);
 void write_source_bank(hid_t group_id);
-void read_source_bank(hid_t group_id);
+void read_source_bank(hid_t group_id, std::vector<Particle::Bank>& sites, bool distribute);
 void write_tally_results_nr(hid_t file_id);
 void restart_set_keff();
 
diff --git a/src/settings.cpp b/src/settings.cpp
index 8e402b7110..5a868d445b 100644
--- a/src/settings.cpp
+++ b/src/settings.cpp
@@ -73,8 +73,6 @@ std::string path_cross_sections;
 std::string path_input;
 std::string path_output;
 std::string path_particle_restart;
-std::string path_source;
-std::string path_source_library;
 std::string path_sourcepoint;
 std::string path_statepoint;
 
@@ -421,17 +419,31 @@ void read_settings_xml()
 
   // Get point to list of <source> elements and make sure there is at least one
   for (pugi::xml_node node : root.children("source")) {
-    model::external_sources.emplace_back(node);
+    if (check_for_node(node, "file")) {
+      auto path = get_node_value(node, "file", false, true);
+      model::external_sources.push_back(std::make_unique<FileSource>(path));
+    } else if (check_for_node(node, "library")) {
+      // Get shared library path and parameters
+      auto path = get_node_value(node, "library", false, true);
+      std::string parameters;
+      if (check_for_node(node, "parameters")) {
+        parameters = get_node_value(node, "parameters", false, true);
+      }
+
+      // Create custom source
+      model::external_sources.push_back(std::make_unique<CustomSourceWrapper>(path, parameters));
+    } else {
+      model::external_sources.push_back(std::make_unique<IndependentSource>(node));
+    }
   }
 
   // If no source specified, default to isotropic point source at origin with Watt spectrum
   if (model::external_sources.empty()) {
-    SourceDistribution source {
+    model::external_sources.push_back(std::make_unique<IndependentSource>(
       UPtrSpace{new SpatialPoint({0.0, 0.0, 0.0})},
       UPtrAngle{new Isotropic()},
       UPtrDist{new Watt(0.988e6, 2.249e-6)}
-    };
-    model::external_sources.push_back(std::move(source));
+    ));
   }
 
   // Check if we want to write out source
diff --git a/src/simulation.cpp b/src/simulation.cpp
index c95c0386c0..1e35adeeea 100644
--- a/src/simulation.cpp
+++ b/src/simulation.cpp
@@ -121,12 +121,6 @@ int openmc_simulation_init()
     }
   }
 
-  // If fixed source and using custom source library then need to load
-  if (settings::run_mode == RunMode::FIXED_SOURCE &&
-      !settings::path_source_library.empty()) {
-    load_custom_source_library();
-  }
-
   // Display header
   if (mpi::master) {
     if (settings::run_mode == RunMode::FIXED_SOURCE) {
@@ -173,12 +167,6 @@ int openmc_simulation_finalize()
     t->active_ = false;
   }
 
-  // If fixed source and using custom source library then need to close
-  if (settings::run_mode == RunMode::FIXED_SOURCE &&
-      !settings::path_source_library.empty()) {
-    close_custom_source_library();
-  }
-
   // Stop timers and show timing statistics
   simulation::time_finalize.stop();
   simulation::time_total.stop();
diff --git a/src/source.cpp b/src/source.cpp
index 4f4ad117bb..87644f054d 100644
--- a/src/source.cpp
+++ b/src/source.cpp
@@ -39,27 +39,18 @@ namespace openmc {
 
 namespace model {
 
-std::vector<SourceDistribution> external_sources;
+std::vector<std::unique_ptr<Source>> external_sources;
 
 }
 
-namespace {
-
-void* custom_source_library;
-std::string custom_source_parameters;
-std::unique_ptr<CustomSource> custom_source;
-
-}
-
-
 //==============================================================================
-// SourceDistribution implementation
+// IndependentSource implementation
 //==============================================================================
 
-SourceDistribution::SourceDistribution(UPtrSpace space, UPtrAngle angle, UPtrDist energy)
+IndependentSource::IndependentSource(UPtrSpace space, UPtrAngle angle, UPtrDist energy)
   : space_{std::move(space)}, angle_{std::move(angle)}, energy_{std::move(energy)} { }
 
-SourceDistribution::SourceDistribution(pugi::xml_node node)
+IndependentSource::IndependentSource(pugi::xml_node node)
 {
   // Check for particle type
   if (check_for_node(node, "particle")) {
@@ -81,24 +72,7 @@ SourceDistribution::SourceDistribution(pugi::xml_node node)
 
   // Check for external source file
   if (check_for_node(node, "file")) {
-    // Copy path of source file
-    settings::path_source = get_node_value(node, "file", false, true);
 
-    // Check if source file exists
-    if (!file_exists(settings::path_source)) {
-      fatal_error(fmt::format("Source file '{}' does not exist.",
-        settings::path_source));
-    }
-  } else if (check_for_node(node, "library")) {
-    settings::path_source_library = get_node_value(node, "library", false, true);
-    if (!file_exists(settings::path_source_library)) {
-      fatal_error(fmt::format("Source library '{}' does not exist.",
-        settings::path_source_library));
-    }
-
-    if (check_for_node(node, "parameters")) {
-      custom_source_parameters = get_node_value(node, "parameters", false, true);
-    }
   } else {
 
     // Spatial distribution for external source
@@ -167,8 +141,7 @@ SourceDistribution::SourceDistribution(pugi::xml_node node)
   }
 }
 
-
-Particle::Bank SourceDistribution::sample(uint64_t* seed) const
+Particle::Bank IndependentSource::sample(uint64_t* seed) const
 {
   Particle::Bank site;
 
@@ -185,10 +158,10 @@ Particle::Bank SourceDistribution::sample(uint64_t* seed) const
 
     // Sample spatial distribution
     site.r = space_->sample(seed);
-    double xyz[] {site.r.x, site.r.y, site.r.z};
 
     // Now search to see if location exists in geometry
     int32_t cell_index, instance;
+    double xyz[] {site.r.x, site.r.y, site.r.z};
     int err = openmc_find_cell(xyz, &cell_index, &instance);
     found = (err != OPENMC_E_GEOMETRY);
 
@@ -256,6 +229,94 @@ Particle::Bank SourceDistribution::sample(uint64_t* seed) const
   return site;
 }
 
+//==============================================================================
+// FileSource implementation
+//==============================================================================
+
+FileSource::FileSource(std::string path)
+{
+  // Check if source file exists
+  if (!file_exists(path)) {
+    fatal_error(fmt::format("Source file '{}' does not exist.", path));
+  }
+
+  // Read the source from a binary file instead of sampling from some
+  // assumed source distribution
+  write_message(6, "Reading source file from {}...", path);
+
+  // Open the binary file
+  hid_t file_id = file_open(path, 'r', true);
+
+  // Check to make sure this is a source file
+  std::string filetype;
+  read_attribute(file_id, "filetype", filetype);
+  if (filetype != "source" && filetype != "statepoint") {
+    fatal_error("Specified starting source file not a source file type.");
+  }
+
+  // Read in the source particles
+  read_source_bank(file_id, sites_, false);
+
+  // Close file
+  file_close(file_id);
+}
+
+Particle::Bank FileSource::sample(uint64_t* seed) const
+{
+  size_t i_site = sites_.size()*prn(seed);
+  return sites_[i_site];
+}
+
+//==============================================================================
+// CustomSourceWrapper implementation
+//==============================================================================
+
+CustomSourceWrapper::CustomSourceWrapper(std::string path, std::string parameters)
+{
+#ifdef HAS_DYNAMIC_LINKING
+  // Open the library
+  shared_library_ = dlopen(path.c_str(), RTLD_LAZY);
+  if (!shared_library_) {
+    fatal_error("Couldn't open source library " + path);
+  }
+
+  // reset errors
+  dlerror();
+
+  // get the function to create the custom source from the library
+  auto create_custom_source = reinterpret_cast<create_custom_source_t*>(
+    dlsym(shared_library_, "openmc_create_source"));
+
+  // check for any dlsym errors
+  auto dlsym_error = dlerror();
+  if (dlsym_error) {
+    std::string error_msg = fmt::format("Couldn't open the openmc_create_source symbol: {}", dlsym_error);
+    dlclose(shared_library_);
+    fatal_error(error_msg);
+  }
+
+  // create a pointer to an instance of the custom source
+  custom_source_ = create_custom_source(parameters);
+
+#else
+  fatal_error("Custom source libraries have not yet been implemented for "
+    "non-POSIX systems");
+#endif
+}
+
+CustomSourceWrapper::~CustomSourceWrapper()
+{
+  // Make sure custom source is cleared before closing shared library
+  if (custom_source_.get()) custom_source_.reset();
+
+#ifdef HAS_DYNAMIC_LINKING
+  dlclose(shared_library_);
+#else
+  fatal_error("Custom source libraries have not yet been implemented for "
+              "non-POSIX systems");
+#endif
+}
+
 //==============================================================================
 // Non-member functions
 //==============================================================================
@@ -264,47 +325,16 @@ void initialize_source()
 {
   write_message("Initializing source particles...", 5);
 
-  if (!settings::path_source.empty()) {
-    // Read the source from a binary file instead of sampling from some
-    // assumed source distribution
+  // Generation source sites from specified distribution in user input
+  #pragma omp parallel for
+  for (int64_t i = 0; i < simulation::work_per_rank; ++i) {
+    // initialize random number seed
+    int64_t id = simulation::total_gen*settings::n_particles +
+      simulation::work_index[mpi::rank] + i + 1;
+    uint64_t seed = init_seed(id, STREAM_SOURCE);
 
-    write_message(6, "Reading source file from {}...", settings::path_source);
-
-    // Open the binary file
-    hid_t file_id = file_open(settings::path_source, 'r', true);
-
-    // Read the file type
-    std::string filetype;
-    read_attribute(file_id, "filetype", filetype);
-
-    // Check to make sure this is a source file
-    if (filetype != "source" && filetype != "statepoint") {
-      fatal_error("Specified starting source file not a source file type.");
-    }
-
-    // Read in the source bank
-    read_source_bank(file_id);
-
-    // Close file
-    file_close(file_id);
-  } else if (!settings::path_source_library.empty()) {
-
-    write_message(6, "Sampling library source {}...", settings::path_source);
-
-    fill_source_bank_custom_source();
-
-  } else {
-    // Generation source sites from specified distribution in user input
-    #pragma omp parallel for
-    for (int64_t i = 0; i < simulation::work_per_rank; ++i) {
-      // initialize random number seed
-      int64_t id = simulation::total_gen*settings::n_particles +
-        simulation::work_index[mpi::rank] + i + 1;
-      uint64_t seed = init_seed(id, STREAM_SOURCE);
-
-      // sample external source distribution
-      simulation::source_bank[i] = sample_external_source(&seed);
-    }
+    // sample external source distribution
+    simulation::source_bank[i] = sample_external_source(&seed);
   }
 
   // Write out initial source
@@ -319,15 +349,10 @@ void initialize_source()
 
 Particle::Bank sample_external_source(uint64_t* seed)
 {
-  // return values from custom source if using
-  if (!settings::path_source_library.empty()) {
-    return sample_custom_source_library(seed);
-  }
-
   // Determine total source strength
   double total_strength = 0.0;
   for (auto& s : model::external_sources)
-    total_strength += s.strength();
+    total_strength += s->strength();
 
   // Sample from among multiple source distributions
   int i = 0;
@@ -335,13 +360,13 @@ Particle::Bank sample_external_source(uint64_t* seed)
     double xi = prn(seed)*total_strength;
     double c = 0.0;
     for (; i < model::external_sources.size(); ++i) {
-      c += model::external_sources[i].strength();
+      c += model::external_sources[i]->strength();
       if (xi < c) break;
     }
   }
 
   // Sample source site from i-th source distribution
-  Particle::Bank site {model::external_sources[i].sample(seed)};
+  Particle::Bank site {model::external_sources[i]->sample(seed)};
 
   // If running in MG, convert site.E to group
   if (!settings::run_CE) {
@@ -358,80 +383,4 @@ void free_memory_source()
   model::external_sources.clear();
 }
 
-void load_custom_source_library()
-{
-#ifdef HAS_DYNAMIC_LINKING
-
-  // Open the library
-  custom_source_library = dlopen(settings::path_source_library.c_str(), RTLD_LAZY);
-  if (!custom_source_library) {
-    fatal_error("Couldn't open source library " + settings::path_source_library);
-  }
-
-  // reset errors
-  dlerror();
-
-  // get the function to create the CustomSource from the library
-  auto create_custom_source = reinterpret_cast<create_custom_source_t*>(
-    dlsym(custom_source_library, "openmc_create_source"));
-
-  // check for any dlsym errors
-  auto dlsym_error = dlerror();
-  if (dlsym_error) {
-    std::string error_msg = fmt::format("Couldn't open the openmc_create_source symbol: {}", dlsym_error);
-    dlclose(custom_source_library);
-    fatal_error(error_msg);
-  }
-
-  // create a pointer to an instance of the CustomSource
-  custom_source = create_custom_source(custom_source_parameters);
-
-#else
-  fatal_error("Custom source libraries have not yet been implemented for "
-    "non-POSIX systems");
-#endif
-}
-
-void close_custom_source_library()
-{
-  if (custom_source.get()) {
-    // Make sure the custom source is destroyed before we close it's libary.
-    custom_source.reset();
-  }
-
-#ifdef HAS_DYNAMIC_LINKING
-  dlclose(custom_source_library);
-#else
-  fatal_error("Custom source libraries have not yet been implemented for "
-              "non-POSIX systems");
-#endif
-}
-
-Particle::Bank sample_custom_source_library(uint64_t* seed)
-{
-  // sample from the instance of the CustomSource
-  return custom_source->sample(seed);
-}
-
-void fill_source_bank_custom_source()
-{
-  // Load the custom library
-  load_custom_source_library();
-
-  // Generation source sites from specified distribution in the
-  // library source
-  for (int64_t i = 0; i < simulation::work_per_rank; ++i) {
-    // initialize random number seed
-    int64_t id = (simulation::total_gen + overall_generation()) *
-      settings::n_particles + simulation::work_index[mpi::rank] + i + 1;
-     uint64_t seed = init_seed(id, STREAM_SOURCE);
-
-    // sample custom library source
-    simulation::source_bank[i] = sample_custom_source_library(&seed);
-  }
-
-  // release the library
-  close_custom_source_library();
-}
-
 } // namespace openmc
diff --git a/src/state_point.cpp b/src/state_point.cpp
index e3484d1a25..66706a676f 100644
--- a/src/state_point.cpp
+++ b/src/state_point.cpp
@@ -485,11 +485,11 @@ void load_state_point()
         + "...", 5);
 
       // Open source file
-      file_id = file_open(settings::path_source.c_str(), 'r', true);
+      file_id = file_open(settings::path_sourcepoint.c_str(), 'r', true);
     }
 
     // Read source
-    read_source_bank(file_id);
+    read_source_bank(file_id, simulation::source_bank, true);
 
   }
 
@@ -653,43 +653,51 @@ write_source_bank(hid_t group_id)
 }
 
 
-void read_source_bank(hid_t group_id)
+void read_source_bank(hid_t group_id, std::vector<Particle::Bank>& sites, bool distribute)
 {
   hid_t banktype = h5banktype();
 
   // Open the dataset
   hid_t dset = H5Dopen(group_id, "source_bank", H5P_DEFAULT);
-
-  // Create another data space but for each proc individually
-  hsize_t dims[] {static_cast<hsize_t>(simulation::work_per_rank)};
-  hid_t memspace = H5Screate_simple(1, dims, nullptr);
-
-  // Make sure source bank is big enough
   hid_t dspace = H5Dget_space(dset);
-  hsize_t dims_all[1];
-  H5Sget_simple_extent_dims(dspace, dims_all, nullptr);
-  if (simulation::work_index[mpi::n_procs] > dims_all[0]) {
-    fatal_error("Number of source sites in source file is less "
-                "than number of source particles per generation.");
-  }
+  hsize_t n_sites;
+  H5Sget_simple_extent_dims(dspace, &n_sites, nullptr);
 
-  // Select hyperslab for each process
-  hsize_t start[] {static_cast<hsize_t>(simulation::work_index[mpi::rank])};
-  H5Sselect_hyperslab(dspace, H5S_SELECT_SET, start, nullptr, dims, nullptr);
+  // Make sure vector is big enough in case where we're reading entire source on
+  // each process
+  if (!distribute) sites.resize(n_sites);
+
+  hid_t memspace;
+  if (distribute) {
+    if (simulation::work_index[mpi::n_procs] > n_sites) {
+      fatal_error("Number of source sites in source file is less "
+                  "than number of source particles per generation.");
+    }
+
+    // Create another data space but for each proc individually
+    hsize_t n_sites_local = simulation::work_per_rank;
+    memspace = H5Screate_simple(1, &n_sites_local, nullptr);
+
+    // Select hyperslab for each process
+    hsize_t offset = simulation::work_index[mpi::rank];
+    H5Sselect_hyperslab(dspace, H5S_SELECT_SET, &offset, nullptr, &n_sites_local, nullptr);
+  } else {
+    memspace = H5S_ALL;
+  }
 
 #ifdef PHDF5
     // Read data in parallel
   hid_t plist = H5Pcreate(H5P_DATASET_XFER);
   H5Pset_dxpl_mpio(plist, H5FD_MPIO_COLLECTIVE);
-  H5Dread(dset, banktype, memspace, dspace, plist, simulation::source_bank.data());
+  H5Dread(dset, banktype, memspace, dspace, plist, sites.data());
   H5Pclose(plist);
 #else
-  H5Dread(dset, banktype, memspace, dspace, H5P_DEFAULT, simulation::source_bank.data());
+  H5Dread(dset, banktype, memspace, dspace, H5P_DEFAULT, sites.data());
 #endif
 
   // Close all ids
   H5Sclose(dspace);
-  H5Sclose(memspace);
+  if (distribute) H5Sclose(memspace);
   H5Dclose(dset);
   H5Tclose(banktype);
 }
diff --git a/src/tallies/tally.cpp b/src/tallies/tally.cpp
index d5cc7dfb6f..038bcec649 100644
--- a/src/tallies/tally.cpp
+++ b/src/tallies/tally.cpp
@@ -632,7 +632,7 @@ void Tally::accumulate()
     double total_source = 0.0;
     if (settings::run_mode == RunMode::FIXED_SOURCE) {
       for (const auto& s : model::external_sources) {
-        total_source += s.strength();
+        total_source += s->strength();
       }
     } else {
       total_source = 1.0;
diff --git a/tests/regression_tests/source_dlopen/source_sampling.cpp b/tests/regression_tests/source_dlopen/source_sampling.cpp
index ea74afdd97..8eaf6265cc 100644
--- a/tests/regression_tests/source_dlopen/source_sampling.cpp
+++ b/tests/regression_tests/source_dlopen/source_sampling.cpp
@@ -5,16 +5,16 @@
 #include "openmc/source.h"
 #include "openmc/particle.h"
 
-class Source : openmc::CustomSource
+class CustomSource : public openmc::Source
 {
-  openmc::Particle::Bank sample(uint64_t *seed)
+  openmc::Particle::Bank sample(uint64_t *seed) const
   {
     openmc::Particle::Bank particle;
     // wgt
     particle.particle = openmc::Particle::Type::neutron;
     particle.wgt = 1.0;
     // position
-    
+
     particle.r.x = 0.;
     particle.r.y = 0.;
     particle.r.z = 0.;
@@ -22,14 +22,14 @@ class Source : openmc::CustomSource
     particle.u = {1.0, 0.0, 0.0};
     particle.E = 14.08e6;
     particle.delayed_group = 0;
-    return particle;    
+    return particle;
   }
 };
 
 // A function to create a unique pointer to an instance of this class when generated
 // via a plugin call using dlopen/dlsym.
 // You must have external C linkage here otherwise dlopen will not find the file
-extern "C" std::unique_ptr<Source> openmc_create_source(std::string parameters)
+extern "C" std::unique_ptr<CustomSource> openmc_create_source(std::string parameters)
 {
-  return std::make_unique<Source>();
+  return std::make_unique<CustomSource>();
 }
diff --git a/tests/regression_tests/source_file/results_true.dat b/tests/regression_tests/source_file/results_true.dat
index 4ab7993d88..44c422eeff 100644
--- a/tests/regression_tests/source_file/results_true.dat
+++ b/tests/regression_tests/source_file/results_true.dat
@@ -1,2 +1,2 @@
 k-combined:
-2.939525E-01 6.311780E-03
+3.080726E-01 9.554124E-03
diff --git a/tests/regression_tests/source_parameterized_dlopen/parameterized_source_sampling.cpp b/tests/regression_tests/source_parameterized_dlopen/parameterized_source_sampling.cpp
index 3b0875bb03..da7d70e378 100644
--- a/tests/regression_tests/source_parameterized_dlopen/parameterized_source_sampling.cpp
+++ b/tests/regression_tests/source_parameterized_dlopen/parameterized_source_sampling.cpp
@@ -1,12 +1,12 @@
 #include "openmc/source.h"
 #include "openmc/particle.h"
 
-class Source : public openmc::CustomSource {
+class CustomSource : public openmc::Source {
   public:
-    Source(double energy) : energy_(energy) { }
+    CustomSource(double energy) : energy_(energy) { }
 
     // Samples from an instance of this class.
-    openmc::Particle::Bank sample(uint64_t* seed)
+    openmc::Particle::Bank sample(uint64_t* seed) const
     {
       openmc::Particle::Bank particle;
       // wgt
@@ -31,8 +31,8 @@ class Source : public openmc::CustomSource {
 // A function to create a unique pointer to an instance of this class when generated
 // via a plugin call using dlopen/dlsym.
 // You must have external C linkage here otherwise dlopen will not find the file
-extern "C" std::unique_ptr<Source> openmc_create_source(std::string parameter)
+extern "C" std::unique_ptr<CustomSource> openmc_create_source(std::string parameter)
 {
   double energy = std::stod(parameter);
-  return std::make_unique<Source>(energy);
+  return std::make_unique<CustomSource>(energy);
 }