diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index f89dd241..56c63e62 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -37,9 +37,9 @@ jobs:
         ocaml-version: ${{ matrix.ocaml-version }}
     - run: opam pin add -n .
     - name: Packages
-      run: opam depext -yt cstruct cstruct-sexp cstruct-unix cstruct-lwt
+      run: opam depext -yt cstruct cstruct-sexp cstruct-unix cstruct-lwt ppx_cstruct
     - name: Build
-      run: opam install -t cstruct cstruct-sexp cstruct-unix cstruct-lwt
+      run: opam install -t cstruct cstruct-sexp cstruct-unix cstruct-lwt ppx_cstruct
   async:
     name: Async
     runs-on: ${{ matrix.operating-system }}
diff --git a/CHANGES.md b/CHANGES.md
index 8d5b2911..0ba0c32a 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,3 +1,12 @@
+v5.1.1 2019-11-23
+-----------------
+
+This is a point release to fix a regression in 5.1.0
+on compilers earlier than 4.07.
+
+The release also fixes the test suite and CI on compilers
+greater than 4.07.
+
 v5.1.0 2019-11-23
 -----------------
 
diff --git a/ppx/dune b/ppx/dune
index bd5d6d6f..bd28df65 100644
--- a/ppx/dune
+++ b/ppx/dune
@@ -3,7 +3,7 @@
  (public_name ppx_cstruct)
  (kind ppx_rewriter)
  (wrapped false)
- (ppx_runtime_libraries cstruct)
+ (ppx_runtime_libraries cstruct stdlib-shims)
  (preprocess
   (pps ppx_tools_versioned.metaquot_404))
  (libraries sexplib ocaml-migrate-parsetree ppx_tools_versioned
diff --git a/ppx_cstruct.opam b/ppx_cstruct.opam
index 27502c3e..131d23f8 100644
--- a/ppx_cstruct.opam
+++ b/ppx_cstruct.opam
@@ -25,6 +25,7 @@ depends: [
   "ppx_sexp_conv" {with-test}
   "sexplib" {>="v0.9.0"}
   "cstruct-sexp" {with-test}
+  "cppo" {with-test}
   "cstruct-unix" {with-test & =version}
   "stdlib-shims"
 ]
diff --git a/ppx_test/errors/dune b/ppx_test/errors/dune
index 7a0eb551..92314158 100644
--- a/ppx_test/errors/dune
+++ b/ppx_test/errors/dune
@@ -1,6 +1,8 @@
 (executable
   (name pp)
   (modules pp)
+  (preprocess (action
+    (run %{bin:cppo} -V OCAML:%{ocaml_version} %{input-file})))
   (libraries
     ppx_cstruct
     ocaml-migrate-parsetree))
diff --git a/ppx_test/errors/gen_tests.ml b/ppx_test/errors/gen_tests.ml
index 65979bfe..ae972b6e 100644
--- a/ppx_test/errors/gen_tests.ml
+++ b/ppx_test/errors/gen_tests.ml
@@ -19,6 +19,7 @@ let output_stanzas name =
 
 let is_test = function
   | "pp.ml" -> false
+  | "pp.pp.ml" -> false
   | "gen_tests.ml" -> false
   | e -> Filename.check_suffix e ".ml"
 
diff --git a/ppx_test/errors/pp.ml b/ppx_test/errors/pp.ml
index b1c1c38c..d10d27b8 100644
--- a/ppx_test/errors/pp.ml
+++ b/ppx_test/errors/pp.ml
@@ -3,4 +3,8 @@
 external sys_exit : int -> 'a = "caml_sys_exit"
 let () = at_exit (fun () -> sys_exit 0)
 
+#if OCAML_VERSION >= (4,8,0)
+let () = Clflags.(error_style := Some Short)
+#endif
+
 let () = Migrate_parsetree.Driver.run_main ()