From 49c7721f75373b3cb5d89bcf7ff3a424198c19e0 Mon Sep 17 00:00:00 2001
From: johnslavik <bartosz@ilikepython.com>
Date: Tue, 17 Mar 2026 14:20:56 +0100
Subject: [PATCH 1/2] Record simple lazy modules as well

---
 Lib/test/test_lazy_import/__init__.py | 15 +++++++++++++++
 Python/import.c                       |  6 ++++++
 2 files changed, 21 insertions(+)

diff --git a/Lib/test/test_lazy_import/__init__.py b/Lib/test/test_lazy_import/__init__.py
index a4180f05dbbafc..043812baad81b6 100644
--- a/Lib/test/test_lazy_import/__init__.py
+++ b/Lib/test/test_lazy_import/__init__.py
@@ -969,6 +969,21 @@ def test_lazy_modules_is_per_interpreter(self):
         # Basic test that sys.lazy_modules exists and is a set
         self.assertIsInstance(sys.lazy_modules, dict)
 
+    def test_lazy_module_without_children_is_tracked(self):
+        code = textwrap.dedent("""
+            import sys
+            lazy import json
+            assert "json" in sys.lazy_modules, (
+                f"expected 'json' in sys.lazy_modules, got {set(sys.lazy_modules)}"
+            )
+            assert sys.lazy_modules["json"] == set(), (
+                f"expected empty set for sys.lazy_modules['json'], "
+                f"got {sys.lazy_modules['json']!r}"
+            )
+            print("OK")
+        """)
+        assert_python_ok("-c", code)
+
 
 @support.requires_subprocess()
 class CommandLineAndEnvVarTests(unittest.TestCase):
diff --git a/Python/import.c b/Python/import.c
index 34224f4c6d6514..875fb05afbcf72 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -4377,6 +4377,12 @@ register_lazy_on_parent(PyThreadState *tstate, PyObject *name,
         Py_ssize_t dot = PyUnicode_FindChar(name, '.', 0,
                                             PyUnicode_GET_LENGTH(name), -1);
         if (dot < 0) {
+            PyObject *lazy_submodules = ensure_lazy_submodules(
+                (PyDictObject *)lazy_modules, name);
+            if (lazy_submodules == NULL) {
+                goto done;
+            }
+            Py_DECREF(lazy_submodules);
             ret = 0;
             goto done;
         }

From 3ee824884e1ce62501fae3ea474e663259ad3feb Mon Sep 17 00:00:00 2001
From: johnslavik <bartosz@ilikepython.com>
Date: Tue, 17 Mar 2026 21:40:59 +0100
Subject: [PATCH 2/2] Add news entry

---
 .../2026-03-17-14-20-56.gh-issue-145059.aB3xKm.rst               | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 Misc/NEWS.d/next/Core_and_Builtins/2026-03-17-14-20-56.gh-issue-145059.aB3xKm.rst

diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2026-03-17-14-20-56.gh-issue-145059.aB3xKm.rst b/Misc/NEWS.d/next/Core_and_Builtins/2026-03-17-14-20-56.gh-issue-145059.aB3xKm.rst
new file mode 100644
index 00000000000000..e2db5a83a1a9e3
--- /dev/null
+++ b/Misc/NEWS.d/next/Core_and_Builtins/2026-03-17-14-20-56.gh-issue-145059.aB3xKm.rst
@@ -0,0 +1 @@
+Fixed ``sys.lazy_modules`` to include lazy modules without submodules. Patch by Bartosz Sławecki.