diff --git a/core/wasm_shims/Python.h b/core/wasm_shims/Python.h
index a330665..4f59713 100644
--- a/core/wasm_shims/Python.h
+++ b/core/wasm_shims/Python.h
@@ -1,3 +1,5 @@
 #pragma once
 
+// LinuxCNC source basis: RS274 Python/remap sources include Python.h through
+// Boost.Python and use the C API declarations provided by this wasm-safe shim.
 #include "boost/python/object.hpp"
diff --git a/core/wasm_shims/python_c_api_shim.cc b/core/wasm_shims/python_c_api_shim.cc
index 96fc444..89fa8fa 100644
--- a/core/wasm_shims/python_c_api_shim.cc
+++ b/core/wasm_shims/python_c_api_shim.cc
@@ -2,6 +2,9 @@
 
 #include <cstdlib>
 
+// LinuxCNC source basis: src/emc/rs274ngc/interp_python.cc,
+// interp_namedparams.cc, gcodemodule.cc, and src/emc/pythonplugin/python_plugin.cc
+// use these Python C API symbols in RS274 Python/remap paths.
 extern "C" {
 
 static PyTypeObject none_type = {"NoneType"};
diff --git a/test-linuxcnc-wasm-cmake-safe-probe.sh b/test-linuxcnc-wasm-cmake-safe-probe.sh
index bae2a32..7127eb8 100755
--- a/test-linuxcnc-wasm-cmake-safe-probe.sh
+++ b/test-linuxcnc-wasm-cmake-safe-probe.sh
@@ -910,6 +910,8 @@ grep -F 'LinuxCNC source basis: src/emc/pythonplugin/python_plugin.cc provides t
 grep -F 'LinuxCNC source basis: src/emc/pythonplugin/python_plugin.hh declares this' core/wasm_shims/pythonplugin/python_plugin.hh >/dev/null
 python_c_api_shim=$(./list-linuxcnc-wasm-safe-shims.sh python_c_api_shim.cc)
 grep -Fx "core/wasm_shims/python_c_api_shim.cc" <<<"$python_c_api_shim" >/dev/null
+grep -F 'LinuxCNC source basis: src/emc/rs274ngc/interp_python.cc,' core/wasm_shims/python_c_api_shim.cc >/dev/null
+grep -F 'LinuxCNC source basis: RS274 Python/remap sources include Python.h through' core/wasm_shims/Python.h >/dev/null
 rtapi_compat_shim=$(./list-linuxcnc-wasm-safe-shims.sh rtapi_compat.cc)
 grep -Fx "core/wasm_shims/rtapi_compat.cc" <<<"$rtapi_compat_shim" >/dev/null
 tooldata_mmap_backend_shim=$(./list-linuxcnc-wasm-safe-shims.sh tooldata_mmap_backend.cc)