diff --git a/session-cohttp-async.opam b/session-cohttp-async.opam
index 51d941a..5942ece 100644
--- a/session-cohttp-async.opam
+++ b/session-cohttp-async.opam
@@ -1,3 +1,4 @@
+version: "0.4.1"
 opam-version: "2.0"
 name: "session-cohttp-async"
 maintainer: "Spiros Eliopoulos <spiros@inhabitedtype.com>"
diff --git a/session-cohttp-lwt.opam b/session-cohttp-lwt.opam
index 49ce435..1fca8b7 100644
--- a/session-cohttp-lwt.opam
+++ b/session-cohttp-lwt.opam
@@ -1,3 +1,4 @@
+version: "0.4.1"
 opam-version: "2.0"
 name: "session-cohttp-lwt"
 maintainer: "Spiros Eliopoulos <spiros@inhabitedtype.com>"
diff --git a/session-cohttp.opam b/session-cohttp.opam
index a147cc1..92e6587 100644
--- a/session-cohttp.opam
+++ b/session-cohttp.opam
@@ -1,3 +1,4 @@
+version: "0.4.1"
 opam-version: "2.0"
 name: "session-cohttp"
 maintainer: "Spiros Eliopoulos <spiros@inhabitedtype.com>"
diff --git a/session-postgresql-async.opam b/session-postgresql-async.opam
index f9a27ce..f42c118 100644
--- a/session-postgresql-async.opam
+++ b/session-postgresql-async.opam
@@ -1,3 +1,4 @@
+version: "0.4.1"
 opam-version: "2.0"
 name: "session-postgresql-async"
 maintainer: "Spiros Eliopoulos <spiros@inhabitedtype.com>"
diff --git a/session-postgresql-lwt.opam b/session-postgresql-lwt.opam
index ae293b1..2cf23d9 100644
--- a/session-postgresql-lwt.opam
+++ b/session-postgresql-lwt.opam
@@ -1,3 +1,4 @@
+version: "0.4.1"
 opam-version: "2.0"
 name: "session-postgresql-lwt"
 maintainer: "Spiros Eliopoulos <spiros@inhabitedtype.com>"
diff --git a/session-postgresql.opam b/session-postgresql.opam
index 660a192..197a7c6 100644
--- a/session-postgresql.opam
+++ b/session-postgresql.opam
@@ -1,3 +1,4 @@
+version: "0.4.1"
 opam-version: "2.0"
 name: "session-postgresql"
 maintainer: "Spiros Eliopoulos <spiros@inhabitedtype.com>"
diff --git a/session-redis-lwt.opam b/session-redis-lwt.opam
index 9bffc63..12f31bf 100644
--- a/session-redis-lwt.opam
+++ b/session-redis-lwt.opam
@@ -1,3 +1,4 @@
+version: "0.4.1"
 opam-version: "2.0"
 name: "session-redis-lwt"
 maintainer: "Spiros Eliopoulos <spiros@inhabitedtype.com>"
diff --git a/session-webmachine.opam b/session-webmachine.opam
index d6727b2..5175a38 100644
--- a/session-webmachine.opam
+++ b/session-webmachine.opam
@@ -1,3 +1,4 @@
+version: "0.4.1"
 opam-version: "2.0"
 name: "session-webmachine"
 maintainer: "Spiros Eliopoulos <spiros@inhabitedtype.com>"
diff --git a/session.opam b/session.opam
index 5a6dc98..5d15760 100644
--- a/session.opam
+++ b/session.opam
@@ -1,3 +1,4 @@
+version: "0.4.1"
 opam-version: "2.0"
 maintainer: "Spiros Eliopoulos <spiros@inhabitedtype.com>"
 authors: "Spiros Eliopoulos <spiros@inhabitedtype.com>"