diff --git a/Objects/exceptions.c b/Objects/exceptions.c
index c8f90b8..a1b79a8 100644
--- a/Objects/exceptions.c
+++ b/Objects/exceptions.c
@@ -1751,8 +1751,8 @@
     if (reason_str == NULL)
         goto done;
 
-    if (uself->start < PyUnicode_GET_SIZE(uself->object) && uself->end == uself->start+1) {
-        int badchar = (int)PyUnicode_AS_UNICODE(uself->object)[uself->start];
+    if (uself->start < PyUnicode_GET_LENGTH(uself->object) && uself->end == uself->start+1) {
+        Py_UCS4 badchar = PyUnicode_ReadChar(uself->object, uself->start);
         const char *fmt;
         if (badchar <= 0xff)
             fmt = "can't translate character '\\x%02x' in position %zd: %U";
@@ -1762,7 +1762,7 @@
             fmt = "can't translate character '\\U%08x' in position %zd: %U";
         result = PyUnicode_FromFormat(
             fmt,
-            badchar,
+            (int)badchar,
             uself->start,
             reason_str
         );