diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 0556eff..8ba379e 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -171,8 +171,8 @@
 #define _PyUnicode_CONVERT_BYTES(from_type, to_type, begin, end, to) \
     do {                                                \
         to_type *_to = (to_type *)(to);                \
-        const from_type *_iter = (from_type *)(begin);  \
-        const from_type *_end = (from_type *)(end);     \
+        const from_type *_iter = (const from_type *)(begin);\
+        const from_type *_end = (const from_type *)(end);\
         Py_ssize_t n = (_end) - (_iter);                \
         const from_type *_unrolled_end =                \
             _iter + _Py_SIZE_ROUND_DOWN(n, 4);          \
@@ -919,21 +919,21 @@
         if ((Py_UCS1) ch != ch)
             return -1;
         if (direction > 0)
-            return ucs1lib_find_char((Py_UCS1 *) s, size, (Py_UCS1) ch);
+            return ucs1lib_find_char((const Py_UCS1 *) s, size, (Py_UCS1) ch);
         else
-            return ucs1lib_rfind_char((Py_UCS1 *) s, size, (Py_UCS1) ch);
+            return ucs1lib_rfind_char((const Py_UCS1 *) s, size, (Py_UCS1) ch);
     case PyUnicode_2BYTE_KIND:
         if ((Py_UCS2) ch != ch)
             return -1;
         if (direction > 0)
-            return ucs2lib_find_char((Py_UCS2 *) s, size, (Py_UCS2) ch);
+            return ucs2lib_find_char((const Py_UCS2 *) s, size, (Py_UCS2) ch);
         else
-            return ucs2lib_rfind_char((Py_UCS2 *) s, size, (Py_UCS2) ch);
+            return ucs2lib_rfind_char((const Py_UCS2 *) s, size, (Py_UCS2) ch);
     case PyUnicode_4BYTE_KIND:
         if (direction > 0)
-            return ucs4lib_find_char((Py_UCS4 *) s, size, ch);
+            return ucs4lib_find_char((const Py_UCS4 *) s, size, ch);
         else
-            return ucs4lib_rfind_char((Py_UCS4 *) s, size, ch);
+            return ucs4lib_rfind_char((const Py_UCS4 *) s, size, ch);
     default:
         Py_UNREACHABLE();
     }
@@ -3353,7 +3353,7 @@
 
     /* Decode via the codec registry */
     buffer = NULL;
-    if (PyBuffer_FillInfo(&info, NULL, (void *)s, size, 1, PyBUF_FULL_RO) < 0)
+    if (PyBuffer_FillInfo(&info, NULL, (const void *)s, size, 1, PyBUF_FULL_RO) < 0)
         goto onError;
     buffer = PyMemoryView_FromBuffer(&info);
     if (buffer == NULL)
@@ -4861,7 +4861,7 @@
             /* Help allocation */
             const char *_p = p;
             while (_p < aligned_end) {
-                unsigned long value = *(unsigned long *) _p;
+                unsigned long value = *(const unsigned long *) _p;
                 if (value & ASCII_CHAR_MASK)
                     break;
                 _p += SIZEOF_LONG;
@@ -5406,7 +5406,7 @@
     PyObject *errorHandler = NULL;
     PyObject *exc = NULL;
 
-    q = (unsigned char *)s;
+    q = (const unsigned char *)s;
     e = q + size;
 
     if (byteorder)
@@ -5731,7 +5731,7 @@
     PyObject *exc = NULL;
     const char *encoding;
 
-    q = (unsigned char *)s;
+    q = (const unsigned char *)s;
     e = q + size;
 
     if (byteorder)
@@ -6660,7 +6660,7 @@
                        const char *errors)
 {
     /* Latin-1 is equivalent to the first 256 ordinals in Unicode. */
-    return _PyUnicode_FromUCS1((unsigned char*)s, size);
+    return _PyUnicode_FromUCS1((const unsigned char*)s, size);
 }
 
 /* create or adjust a UnicodeEncodeError */
@@ -13708,7 +13708,7 @@
     if (len == -1)
         len = strlen(ascii);
 
-    assert(ucs1lib_find_max_char((Py_UCS1*)ascii, (Py_UCS1*)ascii + len) < 128);
+    assert(ucs1lib_find_max_char((const Py_UCS1*)ascii, (const Py_UCS1*)ascii + len) < 128);
 
     if (writer->buffer == NULL && !writer->overallocate) {
         PyObject *str;
@@ -13767,7 +13767,7 @@
 {
     Py_UCS4 maxchar;
 
-    maxchar = ucs1lib_find_max_char((Py_UCS1*)str, (Py_UCS1*)str + len);
+    maxchar = ucs1lib_find_max_char((const Py_UCS1*)str, (const Py_UCS1*)str + len);
     if (_PyUnicodeWriter_Prepare(writer, len, maxchar) == -1)
         return -1;
     unicode_write_cstr(writer->buffer, writer->pos, str, len);