diff --git a/docs/python_interface.md b/docs/python_interface.md
index 6c856291..ad34b352 100644
--- a/docs/python_interface.md
+++ b/docs/python_interface.md
@@ -280,7 +280,8 @@ This does **not** control DDS's batch parallelism and is kept only for backward
 compatibility. `solve_all_boards_*` already parallelize across the machine's
 hardware threads automatically (via `solve_boards_n`) — the value passed here does
 not size that pool. `analyse_all_plays_pbn` currently runs sequentially.
-`user_threads` must be `>= 0` (`0` = auto); raises `ValueError` for negative values.
+`user_threads` is ignored regardless of value (including negative values) — it
+is accepted only for backward compatibility with the legacy call signature.
 
 For per-board concurrency from Python, create one `SolverContext` per worker thread
 and pass it to `solve_board` / `solve_board_pbn` (which release the GIL during the
diff --git a/python/src/bindings.cpp b/python/src/bindings.cpp
index b111e219..c11b4e15 100644
--- a/python/src/bindings.cpp
+++ b/python/src/bindings.cpp
@@ -644,7 +644,7 @@ auto register_analysis_bindings(py::module_& module) -> void
     // count argument is ignored; retained only for backward compatibility.
     module.def(
         "set_max_threads",
-        [](const int user_threads) {
+        [](const int /*user_threads*/) {
             if (PyErr_WarnEx(
                     PyExc_DeprecationWarning,
                     "set_max_threads() is deprecated; use initialize_static_memory(). "
@@ -653,7 +653,7 @@ auto register_analysis_bindings(py::module_& module) -> void
                 throw py::error_already_set();
             }
             py::gil_scoped_release release;
-            SetMaxThreads(user_threads);
+            SetMaxThreads(0);
         },
         py::arg("user_threads") = 0,
         "DEPRECATED: use initialize_static_memory() instead.\n\n"
diff --git a/python/tests/test_analyse.py b/python/tests/test_analyse.py
index 544c5b3e..376b3bc9 100644
--- a/python/tests/test_analyse.py
+++ b/python/tests/test_analyse.py
@@ -1,4 +1,4 @@
-"""Tests for analyse_play_pbn, analyse_all_plays_pbn and dealer_par."""
+"""Tests for analyse_play_pbn, analyse_all_plays_pbn, dealer_par and set_max_threads."""
 
 import unittest
 
@@ -92,5 +92,22 @@ def test_dealer_par_invalid_vulnerability(self) -> None:
             dealer_par(dd_table, dealer=0, vulnerable=9)
 
 
+class TestSetMaxThreads(unittest.TestCase):
+    """Tests for the deprecated set_max_threads() thread-resource hook.
+
+    user_threads is ignored regardless of value (see docs/python_interface.md);
+    it is accepted only for backward compatibility with the legacy call
+    signature, so a negative value must not be rejected.
+    """
+
+    def test_negative_user_threads_is_ignored_not_rejected(self) -> None:
+        with self.assertWarns(DeprecationWarning):
+            set_max_threads(-1)
+
+    def test_emits_deprecation_warning(self) -> None:
+        with self.assertWarns(DeprecationWarning):
+            set_max_threads(0)
+
+
 if __name__ == "__main__":
     unittest.main()