diff --git a/examples/vhdl/external_buffer/cp.py b/examples/vhdl/external_buffer/cp.py
new file mode 100644
index 000000000..971927c69
--- /dev/null
+++ b/examples/vhdl/external_buffer/cp.py
@@ -0,0 +1,31 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this file,
+# You can obtain one at http://mozilla.org/MPL/2.0/.
+#
+# Copyright (c) 2014-2019, Lars Asplund lars.anders.asplund@gmail.com
+
+from vunit import VUnit
+from os import popen
+from os.path import join, dirname
+
+src_path = join(dirname(__file__), 'src')
+
+c_obj = join(src_path, 'cp.o')
+# Compile C application to an object
+print(popen(' '.join([
+    'gcc', '-fPIC',
+    '-c', join(src_path, 'cp.c'),
+    '-o', c_obj
+])).read())
+
+# Enable the external feature for strings
+vu = VUnit.from_argv(vhdl_standard='2008', compile_builtins=False)
+vu.add_builtins({'string': True})
+
+lib = vu.add_library('lib')
+lib.add_source_files(join(src_path, 'tb_extcp_*.vhd'))
+
+# Add the C object to the elaboration of GHDL
+vu.set_sim_option('ghdl.elab_flags', ['-Wl,' + c_obj])
+
+vu.main()
diff --git a/examples/vhdl/external_buffer/run.py b/examples/vhdl/external_buffer/run.py
index 0f207259b..068b5f883 100644
--- a/examples/vhdl/external_buffer/run.py
+++ b/examples/vhdl/external_buffer/run.py
@@ -44,7 +44,7 @@
 vu.add_builtins({'string': True})
 
 lib = vu.add_library('lib')
-lib.add_source_files(join(src_path, '*.vhd'))
+lib.add_source_files(join(src_path, 'tb_ext_*.vhd'))
 
 # Add the C object to the elaboration of GHDL
 vu.set_sim_option('ghdl.elab_flags', ['-Wl,' + c_obj])
diff --git a/examples/vhdl/external_buffer/src/cp.c b/examples/vhdl/external_buffer/src/cp.c
new file mode 100644
index 000000000..dde9c2236
--- /dev/null
+++ b/examples/vhdl/external_buffer/src/cp.c
@@ -0,0 +1,96 @@
+/*
+External Buffer
+
+Interfacing with foreign languages (C) through VHPIDIRECT:
+https://ghdl.readthedocs.io/en/latest/using/Foreign.html
+
+Two arrays of type uint8_t are allocated and some values are written to the first.
+Then, the VHDL simulation is executed, where the (external) array/buffer
+is used. When the simulation is finished, the results are checked. The content of
+the buffer is printed both before and after the simulation.
+
+NOTE: This file is expected to be used along with tb_extcp_byte_vector.vhd or tb_extcp_string.vhd
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+
+extern int ghdl_main (int argc, char **argv);
+
+uint8_t *D[1];
+const uint32_t length = 10;
+
+// Check procedure, to be executed when GHDL exits.
+// The simulation is expected to copy the first 1/3 elements to positions [1/3, 2/3),
+// while incrementing each value by one, and then copy elements from [1/3, 2/3) to
+// [2/3, 3/3), while incrementing each value by two.
+static void exit_handler(void) {
+  int i, j, z, k;
+  uint8_t expected, got;
+  k = 0;
+
+  for(i=0; i<length; i++) {
+    expected = D[0][i];
+    got = D[1][i];
+    if (expected != got) {
+      printf("check error %d: %d %d\n", i, expected, got);
+      exit(1);
+    }
+    printf("%d: %d\n", i, got);
+  }
+
+  free(D[0]);
+  free(D[1]);
+}
+
+// Main entrypoint of the application
+int main(int argc, char **argv) {
+  // Allocate two buffers
+  int i;
+  for(i=0; i<2; i++) {
+    D[i] = (uint8_t *) malloc(length*sizeof(uint8_t));
+    if ( D[i] == NULL ) {
+      perror("execution of malloc() failed!\n");
+      return -1;
+    }
+  }
+  // Initialize the first buffer
+  for(i=0; i<length; i++) {
+    D[0][i] = (i+1)*11;
+  }
+  // Print all the buffer
+  for(i=0; i<length; i++) {
+    printf("%d: %d\n", i, D[0][i]);
+  }
+
+  // Register a function to be called when GHDL exits
+  atexit(exit_handler);
+
+  // Start the simulation
+  return ghdl_main(argc, argv);
+}
+
+// External through access (mode = extacc)
+
+void set_string_ptr(uint8_t id, uint8_t *p) {
+  //printf("C set_string_ptr(%d, %p)\n", id, p);
+  D[id] = p;
+}
+
+uintptr_t get_string_ptr(uint8_t id) {
+  //printf("C get_string_ptr(%d): %p\n", id, D[id]);
+  return (uintptr_t)D[id];
+}
+
+// External through functions (mode = extfnc)
+
+void write_char(uint8_t id, uint32_t i, uint8_t v ) {
+  //printf("C write_char(%d, %d): %d\n", id, i, v);
+  D[id][i] = v;
+}
+
+uint8_t read_char(uint8_t id, uint32_t i) {
+  //printf("C read_char(%d, %d): %d\n", id, i, D[id][i]);
+  return D[id][i];
+}
diff --git a/examples/vhdl/external_buffer/src/tb_extcp_byte_vector.vhd b/examples/vhdl/external_buffer/src/tb_extcp_byte_vector.vhd
new file mode 100644
index 000000000..c59f0536a
--- /dev/null
+++ b/examples/vhdl/external_buffer/src/tb_extcp_byte_vector.vhd
@@ -0,0 +1,48 @@
+-- This Source Code Form is subject to the terms of the Mozilla Public
+-- License, v. 2.0. If a copy of the MPL was not distributed with this file,
+-- You can obtain one at http://mozilla.org/MPL/2.0/.
+--
+-- Copyright (c) 2014-2019, Lars Asplund lars.anders.asplund@gmail.com
+
+-- NOTE: This file is expected to be used along with foreign languages (C)
+-- through VHPIDIRECT: https://ghdl.readthedocs.io/en/latest/using/Foreign.html
+-- See main.c for an example of a wrapper application.
+
+--library vunit_lib;
+--context vunit_lib.vunit_context;
+
+library vunit_lib;
+use vunit_lib.run_pkg.all;
+use vunit_lib.logger_pkg.all;
+use vunit_lib.types_pkg.all;
+use vunit_lib.byte_vector_ptr_pkg.all;
+
+entity tb_extcp_byte_vector is
+  generic ( runner_cfg : string );
+end entity;
+
+architecture tb of tb_extcp_byte_vector is
+
+  constant block_len : natural := 10;
+
+  constant ebuf: byte_vector_ptr_t := new_byte_vector_ptr( block_len, extfnc, 0);  -- external through VHPIDIRECT functions 'read_char' and 'write_char'
+  constant abuf: byte_vector_ptr_t := new_byte_vector_ptr( block_len, extacc, 1);  -- external through access (requires VHPIDIRECT function 'get_string_ptr')
+
+begin
+
+  main: process
+    variable val: integer;
+  begin
+    test_runner_setup(runner, runner_cfg);
+    info("Init test");
+    for x in 0 to block_len-1 loop
+      val := get(ebuf, x);
+      set(abuf, x, val);
+      info("SET " & to_string(x) & ": " & to_string(val));
+    end loop;
+    info("End test");
+    test_runner_cleanup(runner);
+    wait;
+  end process;
+
+end architecture;
diff --git a/examples/vhdl/external_buffer/src/tb_extcp_string.vhd b/examples/vhdl/external_buffer/src/tb_extcp_string.vhd
new file mode 100644
index 000000000..1bbb981c3
--- /dev/null
+++ b/examples/vhdl/external_buffer/src/tb_extcp_string.vhd
@@ -0,0 +1,48 @@
+-- This Source Code Form is subject to the terms of the Mozilla Public
+-- License, v. 2.0. If a copy of the MPL was not distributed with this file,
+-- You can obtain one at http://mozilla.org/MPL/2.0/.
+--
+-- Copyright (c) 2014-2019, Lars Asplund lars.anders.asplund@gmail.com
+
+-- NOTE: This file is expected to be used along with foreign languages (C)
+-- through VHPIDIRECT: https://ghdl.readthedocs.io/en/latest/using/Foreign.html
+-- See main.c for an example of a wrapper application.
+
+--library vunit_lib;
+--context vunit_lib.vunit_context;
+
+library vunit_lib;
+use vunit_lib.run_pkg.all;
+use vunit_lib.logger_pkg.all;
+use vunit_lib.types_pkg.all;
+use vunit_lib.string_ptr_pkg.all;
+
+entity tb_extcp_string is
+  generic ( runner_cfg : string );
+end entity;
+
+architecture tb of tb_extcp_string is
+
+  constant block_len : natural := 10;
+
+  constant ebuf: string_ptr_t := new_string_ptr( block_len, extfnc, 0);  -- external through VHPIDIRECT functions 'read_char' and 'write_char'
+  constant abuf: string_ptr_t := new_string_ptr( block_len, extacc, 1);  -- external through access (requires VHPIDIRECT function 'get_string_ptr')
+
+begin
+
+  main: process
+    variable val: character;
+  begin
+    test_runner_setup(runner, runner_cfg);
+    info("Init test");
+    for x in 1 to block_len loop
+      val := get(ebuf, x);
+      set(abuf, x, val);
+      info("SET " & to_string(x) & ": " & to_string(val));
+    end loop;
+    info("End test");
+    test_runner_cleanup(runner);
+    wait;
+  end process;
+
+end architecture;
diff --git a/vunit/test/acceptance/test_external_run_scripts.py b/vunit/test/acceptance/test_external_run_scripts.py
index 4fcb0f10b..95a8d3eda 100644
--- a/vunit/test/acceptance/test_external_run_scripts.py
+++ b/vunit/test/acceptance/test_external_run_scripts.py
@@ -123,6 +123,7 @@ def test_vhdl_axi_dma_example_project(self):
     )
     def test_vhdl_external_buffer_project(self):
         self.check(join(ROOT, "examples", "vhdl", "external_buffer", "run.py"))
+        self.check(join(ROOT, "examples", "vhdl", "external_buffer", "cp.py"))
 
     def test_vhdl_user_guide_example_project(self):
         self.check(join(ROOT, "examples", "vhdl", "user_guide", "run.py"), exit_code=1)