diff --git a/Misc/NEWS b/Misc/NEWS
index 9909020aef93..161de763e92a 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,9 @@ What's New in Python 3.7.0 alpha 1
 Core and Builtins
 -----------------
 
+- Issue #28648: Fixed crash in Py_DecodeLocale() in debug build on Mac OS X
+  when decode astral characters.  Patch by Xiang Zhang.
+
 - Issue #28665: Improve speed of the STORE_DEREF opcode by 40%.
 
 - Issue #19398: Extra slash no longer added to sys.path components in case of
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index e22eed8853fe..ab363575c5cf 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -5101,7 +5101,7 @@ _Py_DecodeUTF8_surrogateescape(const char *s, Py_ssize_t size)
 #if SIZEOF_WCHAR_T == 4
             assert(0);
 #else
-            assert(Py_UNICODE_IS_SURROGATE(ch));
+            assert(ch > 0xFFFF && ch <= MAX_UNICODE);
             /*  compute and append the two surrogates: */
             unicode[outpos++] = (wchar_t)Py_UNICODE_HIGH_SURROGATE(ch);
             unicode[outpos++] = (wchar_t)Py_UNICODE_LOW_SURROGATE(ch);