diff --git a/cmake/stage_server.cmake b/cmake/stage_server.cmake
index dfbbd5d..2d590a5 100644
--- a/cmake/stage_server.cmake
+++ b/cmake/stage_server.cmake
@@ -41,6 +41,29 @@ if(NOT "${_preserve_admin_token}" STREQUAL "")
     file(WRITE "${_stage_admin_token}" "${_preserve_admin_token}")
 endif()
 
+file(GLOB_RECURSE _prohibited_legacy_files
+    LIST_DIRECTORIES false
+    "${CO_SERVER_STAGE_DIR}/*.py"
+    "${CO_SERVER_STAGE_DIR}/*.pyw"
+    "${CO_SERVER_STAGE_DIR}/*.pyi"
+    "${CO_SERVER_STAGE_DIR}/*.pyc"
+    "${CO_SERVER_STAGE_DIR}/*.pyo"
+    "${CO_SERVER_STAGE_DIR}/*.whl"
+    "${CO_SERVER_STAGE_DIR}/*.egg"
+    "${CO_SERVER_STAGE_DIR}/requirements*.txt"
+    "${CO_SERVER_STAGE_DIR}/Pipfile"
+    "${CO_SERVER_STAGE_DIR}/Pipfile.lock"
+    "${CO_SERVER_STAGE_DIR}/pyproject.toml"
+    "${CO_SERVER_STAGE_DIR}/poetry.lock"
+    "${CO_SERVER_STAGE_DIR}/setup.py"
+    "${CO_SERVER_STAGE_DIR}/setup.cfg"
+    "${CO_SERVER_STAGE_DIR}/tox.ini"
+)
+if(_prohibited_legacy_files)
+    string(JOIN "\n  " _prohibited_list ${_prohibited_legacy_files})
+    message(FATAL_ERROR "Prohibited legacy runtime artifacts were staged:\n  ${_prohibited_list}")
+endif()
+
 if(NOT EXISTS "${CO_SERVER_STAGE_DIR}/CommonwealthOnline.Server${CO_SERVER_EXECUTABLE_SUFFIX}")
     message(FATAL_ERROR "Failed to stage C# server entrypoint")
 endif()