diff --git a/CHANGES.md b/CHANGES.md
index 2aab6bcc..e58fbfd1 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,3 +1,11 @@
+v3.1.1 2017-07-13
+-----------------
+
+- `check_alignment` now treats a large alignment as an unsigned value
+  and so doesnt raise a signal (#171 by @yallop)
+- Improve Windows support by avoiding `void *` pointer arithmetic and
+  have more portable headers in the C stubs (#170 by @fdopen)
+
 v3.1.0 2017-07-12
 -----------------
 
diff --git a/lib_test/tests.ml b/lib_test/tests.ml
index 0312a9eb..44435bc1 100644
--- a/lib_test/tests.ml
+++ b/lib_test/tests.ml
@@ -122,6 +122,9 @@ let check_alignment_zero () =
   with
     Invalid_argument _ -> ()
 
+let check_alignment_large () =
+  assert_equal (Cstruct.(check_alignment (create 1) (Int64.to_int 4294967296L))) false
+
 let _ =
   let suite =
     "misc tests" >::: [
@@ -142,6 +145,7 @@ let _ =
         "aligned to 4096" >:: check_alignment 4096
       ; "aligned to 512"  >:: check_alignment 512
       ; "aligned to 0"  >:: check_alignment_zero
+      ; "aligned to large"  >:: check_alignment_large
       ]
     ]
   in