diff --git a/packages/conf-flint/conf-flint.3.0/opam b/packages/conf-flint/conf-flint.3.0/opam
index 5f6df5e908ef..f4ce2d1bcf21 100644
--- a/packages/conf-flint/conf-flint.3.0/opam
+++ b/packages/conf-flint/conf-flint.3.0/opam
@@ -4,7 +4,12 @@ homepage: "http://flint.org"
 bug-reports: "https://github.com/flintlib/flint2.git"
 license: "LGPL-2.1-only"
 build: [
-  ["sh" "-exc" "printf \"#include  <flint/flint.h>\\n#if __FLINT_VERSION < 3\\n#error \\\"Flint (>= 3.0) is not accessible\\\"\\n#endif\" > test.c"]
+  ["sh" "-exc" "cat <<EOF > test.c 
+    #include  <flint/flint.h>
+    #if __FLINT_VERSION < 3
+    #error \"Flint (>= 3.0) is not accessible\"
+    #endif
+    "]
   ["sh" "-exc" "cc -c $CFLAGS -I/usr/local/include test.c"] {os != "macos" & os != "win32"}
   [
 		"sh"
@@ -22,12 +27,14 @@ depexts: [
   ["libflint-dev"] {os-distribution = "ubuntu" }
   ["flint"] {os = "macos" & os-distribution = "homebrew"}
   ["flint"] {os-distribution = "macports" & os = "macos"}
-  ["flint" "flint-devel"] {os-distribution = "centos"}
   ["flint" "flint-devel"] {os-family = "fedora"}
   ["flint" "flint-devel"] {os-distribution = "ol"}
-  ["flint-dev"] {os-distribution = "alpine"}
+  ["flint-dev@testing"] {os-distribution = "alpine"}
   ["flint-devel"] {os-family = "opensuse"}
-  ["libflint-devel"] {os = "win32" & os-distribution = "cygwinports"}
+  ["libflint-devel"] {os = "win32" &
+                         (os-distribution = "cygwinports" |
+                          os-distribution = "cygwin") }
+  ["mingw-w64-flint"] {os = "win32" & os-distribution = "msys2" }
   ["flint"] {os-distribution = "nixos"}
   ["flint"] {os-distribution = "arch"}
 ]
diff --git a/packages/flint/flint.0.4.2/opam b/packages/flint/flint.0.4.2/opam
new file mode 100644
index 000000000000..692954dab948
--- /dev/null
+++ b/packages/flint/flint.0.4.2/opam
@@ -0,0 +1,48 @@
+opam-version: "2.0"
+synopsis: "Stub of the C library Flint3"
+maintainer: ["François Bobot"]
+authors: ["François Bobot"]
+license: "LGPL-2.1-only"
+homepage: "https://github.com/bobot/ocaml-flint"
+bug-reports: "https://github.com/bobot/ocaml-flint/issues"
+depends: [
+  "dune" {>= "3.7"}
+  "conf-flint" {>= "3.0"}
+  "zarith" {>= "1.12"}
+  "ctypes" {>= "0.20.1"}
+  "conf-mpfr" {>= "3"}
+  "dune-site" {with-test}
+  "ocaml" {>= "4.10"}
+  "conf-pkg-config" {>= "2"}
+  "dune-configurator"
+  "odoc" {with-doc}
+]
+build: [
+  ["dune" "subst"] {dev}
+  [
+    "dune"
+    "build"
+    "-p"
+    name
+    "-j"
+    jobs
+    "@install"
+    "@runtest" {with-test}
+    "@doc" {with-doc}
+  ]
+]
+dev-repo: "git+https://github.com/bobot/ocaml-flint.git"
+conflicts: [ "ocaml-option-bytecode-only" ]
+messages: [ "Problem with the installation of the external
+             libraries can be fixed using version 0.3 which
+             compile them locally" { failure } ]
+x-maintenance-intent: ["(latest)"]
+url {
+  src:
+    "https://github.com/bobot/ocaml-flint/releases/download/0.4.2/flint-0.4.2.tbz"
+  checksum: [
+    "sha256=86fe0db578d7e21160528c07ffdc80375e649371e1c5fbc9f50aafd99ca1ddba"
+    "sha512=8f5d75f40eb1e9b8cc7585da01cbe836d552540d4551080cf986c6faf68e5006621a39c37cf1147d4e71b056ff90f80166eea08e5425d30297e2239188730a4e"
+  ]
+}
+x-commit-hash: "c75621d4342b7792e21413beabfb8562949a2b2f"
\ No newline at end of file