diff --git a/Python/codecs.c b/Python/codecs.c
index 0b736c1..ea33c49 100644
--- a/Python/codecs.c
+++ b/Python/codecs.c
@@ -727,7 +727,7 @@
         Py_ssize_t end;
         PyObject *res;
         unsigned char *outp;
-        int ressize;
+        Py_ssize_t ressize;
         Py_UCS4 ch;
         if (PyUnicodeEncodeError_GetStart(exc, &start))
             return NULL;
@@ -735,6 +735,8 @@
             return NULL;
         if (!(object = PyUnicodeEncodeError_GetObject(exc)))
             return NULL;
+        if (end - start > PY_SSIZE_T_MAX / (2+7+1))
+            end = start + PY_SSIZE_T_MAX / (2+7+1);
         for (i = start, ressize = 0; i < end; ++i) {
             /* object is guaranteed to be "ready" */
             ch = PyUnicode_READ_CHAR(object, i);
@@ -823,7 +825,7 @@
         Py_ssize_t end;
         PyObject *res;
         unsigned char *outp;
-        int ressize;
+        Py_ssize_t ressize;
         Py_UCS4 c;
         if (PyUnicodeEncodeError_GetStart(exc, &start))
             return NULL;
@@ -831,6 +833,8 @@
             return NULL;
         if (!(object = PyUnicodeEncodeError_GetObject(exc)))
             return NULL;
+        if (end - start > PY_SSIZE_T_MAX / (1+1+8))
+            end = start + PY_SSIZE_T_MAX / (1+1+8);
         for (i = start, ressize = 0; i < end; ++i) {
             /* object is guaranteed to be "ready" */
             c = PyUnicode_READ_CHAR(object, i);