diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index a7a3151..f6bf505 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -5070,25 +5070,16 @@ static Py_ssize_t
 ascii_decode(const char *start, const char *end, Py_UCS1 *dest)
 {
     const char *p = start;
-    const char *aligned_end = (const char *) _Py_ALIGN_DOWN(end, SIZEOF_SIZE_T);
 
-    /*
-     * Issue #17237: m68k is a bit different from most architectures in
-     * that objects do not use "natural alignment" - for example, int and
-     * long are only aligned at 2-byte boundaries.  Therefore the assert()
-     * won't work; also, tests have shown that skipping the "optimised
-     * version" will even speed up m68k.
-     */
-#if !defined(__m68k__)
 #if SIZEOF_SIZE_T <= SIZEOF_VOID_P
-    assert(_Py_IS_ALIGNED(dest, SIZEOF_SIZE_T));
-    if (_Py_IS_ALIGNED(p, SIZEOF_SIZE_T)) {
+    assert(_Py_IS_ALIGNED(dest, ALIGNOF_SIZE_T));
+    if (_Py_IS_ALIGNED(p, ALIGNOF_SIZE_T)) {
         /* Fast path, see in STRINGLIB(utf8_decode) for
            an explanation. */
         /* Help allocation */
         const char *_p = p;
         Py_UCS1 * q = dest;
-        while (_p < aligned_end) {
+        while (_p + SIZEOF_SIZE_T <= end) {
             size_t value = *(const size_t *) _p;
             if (value & ASCII_CHAR_MASK)
                 break;
@@ -5105,14 +5096,13 @@ ascii_decode(const char *start, const char *end, Py_UCS1 *dest)
         return p - start;
     }
 #endif
-#endif
     while (p < end) {
         /* Fast path, see in STRINGLIB(utf8_decode) in stringlib/codecs.h
            for an explanation. */
-        if (_Py_IS_ALIGNED(p, SIZEOF_SIZE_T)) {
+        if (_Py_IS_ALIGNED(p, ALIGNOF_SIZE_T)) {
             /* Help allocation */
             const char *_p = p;
-            while (_p < aligned_end) {
+            while (_p + SIZEOF_SIZE_T <= end) {
                 size_t value = *(const size_t *) _p;
                 if (value & ASCII_CHAR_MASK)
                     break;