diff --git a/Objects/longobject.c b/Objects/longobject.c
index 3630ae4..74c59c7 100644
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -1657,6 +1657,7 @@
 
     /* check we've counted correctly */
     assert(p == PyUnicode_1BYTE_DATA(str));
+    assert(_PyUnicode_CheckConsistency(str, 1));
     Py_DECREF(scratch);
     return (PyObject *)str;
 }
@@ -1761,6 +1762,7 @@
     if (negative)
         *--p = '-';
     assert(p == PyUnicode_1BYTE_DATA(v));
+    assert(_PyUnicode_CheckConsistency(v, 1));
     return v;
 }