diff --git a/angstrom-async.opam b/angstrom-async.opam
index 06ccdb3..5ecba6f 100644
--- a/angstrom-async.opam
+++ b/angstrom-async.opam
@@ -1,3 +1,4 @@
+version: "0.8.1"
 opam-version: "1.2"
 name: "angstrom-async"
 maintainer: "Spiros Eliopoulos <spiros@inhabitedtype.com>"
diff --git a/angstrom-lwt-unix.opam b/angstrom-lwt-unix.opam
index 7646d66..024c9ea 100644
--- a/angstrom-lwt-unix.opam
+++ b/angstrom-lwt-unix.opam
@@ -1,3 +1,4 @@
+version: "0.8.1"
 opam-version: "1.2"
 maintainer: "Spiros Eliopoulos <spiros@inhabitedtype.com>"
 authors: [ "Spiros Eliopoulos <spiros@inhabitedtype.com>" ]
diff --git a/angstrom-unix.opam b/angstrom-unix.opam
index d833b4d..77d82e5 100644
--- a/angstrom-unix.opam
+++ b/angstrom-unix.opam
@@ -1,3 +1,4 @@
+version: "0.8.1"
 opam-version: "1.2"
 maintainer: "Spiros Eliopoulos <spiros@inhabitedtype.com>"
 authors: [ "Spiros Eliopoulos <spiros@inhabitedtype.com>" ]
diff --git a/angstrom.opam b/angstrom.opam
index d6cc95b..6072968 100644
--- a/angstrom.opam
+++ b/angstrom.opam
@@ -1,3 +1,4 @@
+version: "0.8.1"
 opam-version: "1.2"
 maintainer: "Spiros Eliopoulos <spiros@inhabitedtype.com>"
 authors: [ "Spiros Eliopoulos <spiros@inhabitedtype.com>" ]