diff --git a/session-cohttp-async.opam b/session-cohttp-async.opam
index 55d5b7e..ede3eb3 100644
--- a/session-cohttp-async.opam
+++ b/session-cohttp-async.opam
@@ -1,3 +1,4 @@
+version: "0.4.0"
 opam-version: "1.2"
 name: "session"
 maintainer: "Spiros Eliopoulos <spiros@inhabitedtype.com>"
diff --git a/session-cohttp-lwt.opam b/session-cohttp-lwt.opam
index 3f86e6b..a4816e8 100644
--- a/session-cohttp-lwt.opam
+++ b/session-cohttp-lwt.opam
@@ -1,3 +1,4 @@
+version: "0.4.0"
 opam-version: "1.2"
 name: "session"
 maintainer: "Spiros Eliopoulos <spiros@inhabitedtype.com>"
diff --git a/session-cohttp.opam b/session-cohttp.opam
index c230645..5c19c9d 100644
--- a/session-cohttp.opam
+++ b/session-cohttp.opam
@@ -1,3 +1,4 @@
+version: "0.4.0"
 opam-version: "1.2"
 name: "session"
 maintainer: "Spiros Eliopoulos <spiros@inhabitedtype.com>"
diff --git a/session-postgresql-async.opam b/session-postgresql-async.opam
index be8b0c3..bf27386 100644
--- a/session-postgresql-async.opam
+++ b/session-postgresql-async.opam
@@ -1,3 +1,4 @@
+version: "0.4.0"
 opam-version: "1.2"
 name: "session"
 maintainer: "Spiros Eliopoulos <spiros@inhabitedtype.com>"
diff --git a/session-postgresql-lwt.opam b/session-postgresql-lwt.opam
index 50705d4..13a09d7 100644
--- a/session-postgresql-lwt.opam
+++ b/session-postgresql-lwt.opam
@@ -1,3 +1,4 @@
+version: "0.4.0"
 opam-version: "1.2"
 name: "session"
 maintainer: "Spiros Eliopoulos <spiros@inhabitedtype.com>"
diff --git a/session-postgresql.opam b/session-postgresql.opam
index 21082a2..06519ba 100644
--- a/session-postgresql.opam
+++ b/session-postgresql.opam
@@ -1,3 +1,4 @@
+version: "0.4.0"
 opam-version: "1.2"
 name: "session"
 maintainer: "Spiros Eliopoulos <spiros@inhabitedtype.com>"
diff --git a/session-redis-lwt.opam b/session-redis-lwt.opam
index 1aa4ba3..645e508 100644
--- a/session-redis-lwt.opam
+++ b/session-redis-lwt.opam
@@ -1,3 +1,4 @@
+version: "0.4.0"
 opam-version: "1.2"
 name: "session"
 maintainer: "Spiros Eliopoulos <spiros@inhabitedtype.com>"
diff --git a/session-webmachine.opam b/session-webmachine.opam
index a03ab8e..7cdb850 100644
--- a/session-webmachine.opam
+++ b/session-webmachine.opam
@@ -1,3 +1,4 @@
+version: "0.4.0"
 opam-version: "1.2"
 name: "session"
 maintainer: "Spiros Eliopoulos <spiros@inhabitedtype.com>"
diff --git a/session.opam b/session.opam
index 6c54187..bdd185d 100644
--- a/session.opam
+++ b/session.opam
@@ -1,3 +1,4 @@
+version: "0.4.0"
 opam-version: "1.2"
 name: "session"
 maintainer: "Spiros Eliopoulos <spiros@inhabitedtype.com>"