diff --git a/.travis.yml b/.travis.yml
index fe44134..348297e 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,7 +6,9 @@ install: wget https://raw.githubusercontent.com/ocaml/ocaml-travisci-skeleton/ma
 script: bash -ex ./.travis-docker.sh
 env:
   matrix:
-  - PACKAGE="bigstringaf" DISTRO="ubuntu-16.04" OCAML_VERSION="4.03.0"
-  - PACKAGE="bigstringaf" DISTRO="ubuntu-16.04" OCAML_VERSION="4.04.2"
-  - PACKAGE="bigstringaf" DISTRO="ubuntu-16.04" OCAML_VERSION="4.05.0"
-  - PACKAGE="bigstringaf" DISTRO="ubuntu-16.04" OCAML_VERSION="4.06.0"
+  - PACKAGE="bigstringaf" DISTRO="ubuntu-16.04" OCAML_VERSION="4.03"
+  - PACKAGE="bigstringaf" DISTRO="ubuntu-16.04" OCAML_VERSION="4.04"
+  - PACKAGE="bigstringaf" DISTRO="ubuntu-16.04" OCAML_VERSION="4.05" DEPOPTS="mirage-xen-posix"
+  - PACKAGE="bigstringaf" DISTRO="ubuntu-16.04" OCAML_VERSION="4.06" DEPOPTS="ocaml-freestanding"
+  - PACKAGE="bigstringaf" DISTRO="ubuntu-16.04" OCAML_VERSION="4.06" DEPOPTS="ocaml-freestanding"
+  - PACKAGE="bigstringaf" DISTRO="ubuntu-16.04" OCAML_VERSION="4.07" DEPOPTS="ocaml-freestanding"
diff --git a/CHANGES.md b/CHANGES.md
index 043ea0d..89fe10e 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,8 +1,9 @@
-### 0.4.0 (2018-10-23)
+### 0.4.0 (2018-10-26)
 
-* unify usage of mirage-xen-posix package (#17 @hannesm)
+* freestanding: fix dependencies (ocaml-freestanding #22 @hannesm)
+* xen: unify usage of mirage-xen-posix package (#17 @hannesm)
 * fix typo in comment (#18 @tiensonqin)
-* jbuild: do not use bash (#16 @rgrinberg)
+* jbuild: do not use bash (#16 #21 @rgrinberg, #22 @hannesm)
 * opam: add '"-p" name' to subst command (#15 @seliopou)
 
 ### 0.3.0 (2018-07-07)
diff --git a/bigstringaf.opam b/bigstringaf.opam
index 36ef484..9d67823 100644
--- a/bigstringaf.opam
+++ b/bigstringaf.opam
@@ -20,6 +20,9 @@ depopts: [
   "mirage-xen-posix"
   "ocaml-freestanding"
 ]
+conflicts: [
+  "ocaml-freestanding" {< "0.4.1"}
+]
 synopsis: "Bigstring intrinsics and fast blits based on memcpy/memmove"
 description: """
 Bigstring intrinsics and fast blits based on memcpy/memmove
diff --git a/lib/freestanding/jbuild b/lib/freestanding/jbuild
index a9efd2f..05cf397 100644
--- a/lib/freestanding/jbuild
+++ b/lib/freestanding/jbuild
@@ -4,10 +4,10 @@
  ((name        bigstringaf_freestanding)
   (public_name bigstringaf.freestanding)
   (optional)
-  (libraries   (bigarray mirage-solo5))
+  (libraries   (bigarray ocaml-freestanding))
   (c_names     (bigstringaf_stubs))
   (c_flags     (:include cflags.sexp))))
 
 (rule (copy# ../bigstringaf_stubs.c bigstringaf_stubs.c))
 
-(rule (with-stdout-to cflags.sexp (run cflags.sh)))
+(rule (with-stdout-to cflags.sexp (run ./cflags.sh)))
diff --git a/lib/xen/jbuild b/lib/xen/jbuild
index 32cf85a..ebdb4b5 100644
--- a/lib/xen/jbuild
+++ b/lib/xen/jbuild
@@ -10,4 +10,4 @@
 
 (rule (copy# ../bigstringaf_stubs.c bigstringaf_stubs.c))
 
-(rule (with-stdout-to cflags.sexp (run cflags.sh)))
+(rule (with-stdout-to cflags.sexp (run ./cflags.sh)))