diff --git a/core/wasm_shims/boost/noncopyable.hpp b/core/wasm_shims/boost/noncopyable.hpp
index aa56bda..9a59be1 100644
--- a/core/wasm_shims/boost/noncopyable.hpp
+++ b/core/wasm_shims/boost/noncopyable.hpp
@@ -1,6 +1,8 @@
 #ifndef CNC_SIM_WASM_SHIMS_BOOST_NONCOPYABLE_HPP
 #define CNC_SIM_WASM_SHIMS_BOOST_NONCOPYABLE_HPP
 
+// LinuxCNC source basis: src/emc/rs274ngc/interp_base.hh derives InterpBase
+// from boost::noncopyable.
 namespace boost {
 
 class noncopyable {
diff --git a/core/wasm_shims/boost/python/object.hpp b/core/wasm_shims/boost/python/object.hpp
index 8932a21..9c11520 100644
--- a/core/wasm_shims/boost/python/object.hpp
+++ b/core/wasm_shims/boost/python/object.hpp
@@ -1,5 +1,8 @@
 #pragma once
 
+// LinuxCNC source basis: src/emc/rs274ngc/interp_python.cc,
+// interp_namedparams.cc, rs274ngc_pre.cc, and src/emc/pythonplugin/python_plugin.hh
+// use Boost.Python object/handle/extract APIs in Python/remap paths.
 #include <cstddef>
 #include <cstdarg>
 #include <sstream>
diff --git a/test-linuxcnc-wasm-cmake-safe-probe.sh b/test-linuxcnc-wasm-cmake-safe-probe.sh
index b5db879..88cfd7e 100755
--- a/test-linuxcnc-wasm-cmake-safe-probe.sh
+++ b/test-linuxcnc-wasm-cmake-safe-probe.sh
@@ -1409,8 +1409,10 @@ grep -F 'target_compile_options(linuxcnc_rs274_wasm_safe_probe PRIVATE ${cnc_sim
 grep -F 'target_compile_options(cnc_sim_objects PRIVATE ${cnc_sim_wasm_safe_preinclude_options})' core/CMakeLists.txt >/dev/null
 grep -F 'target_compile_options(cnc_sim_wasm_runtime_probe PRIVATE ${cnc_sim_wasm_safe_preinclude_options})' core/CMakeLists.txt >/dev/null
 test -f core/wasm_shims/boost/noncopyable.hpp
+grep -F 'LinuxCNC source basis: src/emc/rs274ngc/interp_base.hh derives InterpBase' core/wasm_shims/boost/noncopyable.hpp >/dev/null
 grep -F 'class noncopyable' core/wasm_shims/boost/noncopyable.hpp >/dev/null
 grep -F 'noncopyable(const noncopyable &) = delete;' core/wasm_shims/boost/noncopyable.hpp >/dev/null
+grep -F 'LinuxCNC source basis: src/emc/rs274ngc/interp_python.cc,' core/wasm_shims/boost/python/object.hpp >/dev/null
 test -f core/wasm_shims/libgen.h
 grep -F 'LinuxCNC source basis: src/emc/rs274ngc/interp_o_word.cc uses basename()' core/wasm_shims/libgen.h >/dev/null
 grep -F 'inline char *basename(const char *path)' core/wasm_shims/libgen.h >/dev/null