diff --git a/Misc/NEWS.d/next/Library/2026-07-21-16-13-43.gh-issue-154385.yQ6D2V.rst b/Misc/NEWS.d/next/Library/2026-07-21-16-13-43.gh-issue-154385.yQ6D2V.rst
new file mode 100644
index 000000000000000..1c86b0d38bc6f68
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-07-21-16-13-43.gh-issue-154385.yQ6D2V.rst
@@ -0,0 +1,2 @@
+Fix a potential crash in :func:`readline.get_begidx` and
+:func:`readline.get_endidx` caused by an out-of-memory error.
diff --git a/Modules/readline.c b/Modules/readline.c
index 4c965e081c9d1a7..e160bd269c67039 100644
--- a/Modules/readline.c
+++ b/Modules/readline.c
@@ -1325,10 +1325,19 @@ flex_complete(const char *text, int start, int end)
 
 done:
     if (state) {
-        Py_XDECREF(state->begidx);
-        Py_XDECREF(state->endidx);
-        state->begidx = PyLong_FromLong((long) start);
-        state->endidx = PyLong_FromLong((long) end);
+        PyObject *begidx = PyLong_FromLong((long) start);
+        PyObject *endidx = PyLong_FromLong((long) end);
+        if (begidx == NULL || endidx == NULL) {
+            /* Keep the previous values so that get_begidx() and
+               get_endidx() never return NULL. */
+            PyErr_Clear();
+            Py_XDECREF(begidx);
+            Py_XDECREF(endidx);
+        }
+        else {
+            Py_XSETREF(state->begidx, begidx);
+            Py_XSETREF(state->endidx, endidx);
+        }
     }
     result = completion_matches((char *)text, *on_completion);
     PyGILState_Release(gilstate);