--- emacs-25.3-orig/src/alloc.c
+++ emacs-25.3/src/alloc.c
@@ -4892,7 +4892,8 @@
   for (pp = start; (void *) pp < end; pp += GC_POINTER_ALIGNMENT)
     {
       mark_maybe_pointer (*(void **) pp);
-      mark_maybe_object (*(Lisp_Object *) pp);
+      if ((intptr_t) pp % alignof (Lisp_Object) == 0)
+	mark_maybe_object (*(Lisp_Object *) pp);
     }
 }