python
diff --git a/‎Lib/test/test_marshal.py‎
Lines changed: 8 additions & 0 deletions b/‎Lib/test/test_marshal.py‎
Lines changed: 8 additions & 0 deletions
diff --git a/‎Misc/NEWS.d/next/Library/2026-09-13-07-14-35.gh-issue-128509.9F2GCE.rst‎
Lines changed: 2 additions & 0 deletions b/‎Misc/NEWS.d/next/Library/2026-09-13-07-14-35.gh-issue-128509.9F2GCE.rst‎
Lines changed: 2 additions & 0 deletions
diff --git a/‎Python/marshal.c‎
Lines changed: 2 additions & 6 deletions b/‎Python/marshal.c‎
Lines changed: 2 additions & 6 deletions
@@ -116,6 +116,14 @@ def test_bytes(self):
         for s in [b"", b"Andr\xe8 Previn", b"abc", b" "*10000]:
             self.helper(s)
 
+    @support.cpython_only
+    def test_bytes_singleton(self):
+        for version in range(marshal.version + 1):
+            for sample in [b"", b"x"]:
+                new = marshal.loads(marshal.dumps(sample, version))
+                self.assertIs(new, sample)
+
+
 class ExceptionTestCase(unittest.TestCase):
     def test_exceptions(self):
         new = marshal.loads(marshal.dumps(StopIteration))
 
@@ -0,0 +1,2 @@
+:func:`marshal.load` and :func:`marshal.loads` can now get 1-byte string
+singletons. Patch by Victor Stinner.
@@ -1388,16 +1388,12 @@ r_object(RFILE *p)
                 }
                 break;
             }
-            v = PyBytes_FromStringAndSize((char *)NULL, n);
-            if (v == NULL)
-                break;
             ptr = r_string(n, p);
             if (ptr == NULL) {
-                Py_DECREF(v);
                 break;
             }
-            memcpy(PyBytes_AS_STRING(v), ptr, n);
-            retval = v;
+            // Get a singleton for 1-byte string
+            retval = PyBytes_FromStringAndSize(ptr, n);  // can be NULL
             R_REF(retval);
             break;
         }
Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,2 @@`
	`1`	+:func:`marshal.load` and :func:`marshal.loads` can now get 1-byte string
	`2`	`+singletons. Patch by Victor Stinner.`
Original file line number	Diff line number	Diff line change
`@@ -1388,16 +1388,12 @@ r_object(RFILE *p)`
`1388`	`1388`	`}`
`1389`	`1389`	`break;`
`1390`	`1390`	`}`
`1391`		`- v = PyBytes_FromStringAndSize((char *)NULL, n);`
`1392`		`- if (v == NULL)`
`1393`		`- break;`
`1394`	`1391`	`ptr = r_string(n, p);`
`1395`	`1392`	`if (ptr == NULL) {`
`1396`		`- Py_DECREF(v);`
`1397`	`1393`	`break;`
`1398`	`1394`	`}`
`1399`		`- memcpy(PyBytes_AS_STRING(v), ptr, n);`
`1400`		`- retval = v;`
	`1395`	`+ // Get a singleton for 1-byte string`
	`1396`	`+ retval = PyBytes_FromStringAndSize(ptr, n); // can be NULL`
`1401`	`1397`	`R_REF(retval);`
`1402`	`1398`	`break;`
`1403`	`1399`	`}`