diff --git a/src/slic3r/plugin/PythonInterpreter.cpp b/src/slic3r/plugin/PythonInterpreter.cpp
index 4a08431117..89dc91723c 100644
--- a/src/slic3r/plugin/PythonInterpreter.cpp
+++ b/src/slic3r/plugin/PythonInterpreter.cpp
@@ -584,6 +584,19 @@ bool PythonInterpreter::initialize()
         }
         BOOST_LOG_TRIVIAL(debug) << "Program name set successfully";
 
+        // Keep bytecode out of the Python home. The shipped .pyc files are stale against their
+        // sources, so a writable install would rewrite them inside the app (breaking a signed
+        // macOS bundle's seal) and a read-only one would recompile them on every launch.
+        const std::string pycache_prefix = data_dir() + "/python/pycache";
+#ifdef _WIN32
+        status = PyConfig_SetString(&config, &config.pycache_prefix, boost::nowide::widen(pycache_prefix).c_str());
+#else
+        status = PyConfig_SetBytesString(&config, &config.pycache_prefix, pycache_prefix.c_str());
+#endif
+        if (PyStatus_Exception(status))
+            BOOST_LOG_TRIVIAL(warning) << "Failed to set the Python bytecode cache to " << pycache_prefix << ": "
+                                       << (status.err_msg ? status.err_msg : "unknown error");
+
         // Use pybind11's scoped_interpreter which properly initializes
         // pybind11 internals for multi-threaded use — raw Py_InitializeFromConfig
         // does not set up thread state tracking that pybind11 requires.
diff --git a/tests/slic3rutils/test_plugin_lifecycle.cpp b/tests/slic3rutils/test_plugin_lifecycle.cpp
index 58a4f1a079..498935c2f6 100644
--- a/tests/slic3rutils/test_plugin_lifecycle.cpp
+++ b/tests/slic3rutils/test_plugin_lifecycle.cpp
@@ -615,8 +615,22 @@ TEST_CASE("Python module release removes package submodules and owned sys.path",
 
     // Ensure the next import executes the new submodule rather than reusing a stale package child.
     write_package("'new'");
-    boost::system::error_code ec;
-    fs::remove_all(package_root / "__pycache__", ec);
+    {
+        // The rewrite can keep the old mtime and size, so drop the bytecode wherever the
+        // interpreter caches it.
+        PythonGILState gil;
+        REQUIRE(gil);
+        PyObjectPtr util(PyImport_ImportModule("importlib.util"));
+        REQUIRE(util);
+        for (const char* file : {"__init__.py", "sub.py"}) {
+            PyObjectPtr source(PyUnicode_DecodeFSDefault((package_root / file).string().c_str()));
+            REQUIRE(source);
+            PyObjectPtr cached(PyObject_CallMethod(util.get(), "cache_from_source", "O", source.get()));
+            REQUIRE(cached);
+            boost::system::error_code ec;
+            fs::remove(fs::path(PyUnicode_AsUTF8(cached.get())), ec);
+        }
+    }
 
     paths.clear();
     modules.clear();