diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 5fd2372..2ccec90 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -9308,7 +9308,7 @@
             case 's':
             case 'r':
             case 'a':
-                if (PyUnicode_Check(v) && c == 's') {
+                if (PyUnicode_CheckExact(v) && c == 's') {
                     temp = v;
                     Py_INCREF(temp);
                 }