diff --git a/httpaf-async.opam b/httpaf-async.opam
index 4c8d7dff..70f99bea 100644
--- a/httpaf-async.opam
+++ b/httpaf-async.opam
@@ -1,3 +1,4 @@
+version: "0.6.4"
 opam-version: "2.0"
 name: "httpaf-async"
 maintainer: "Spiros Eliopoulos <spiros@inhabitedtype.com>"
diff --git a/httpaf-lwt-unix.opam b/httpaf-lwt-unix.opam
index 1ff418f3..a21f7bb6 100644
--- a/httpaf-lwt-unix.opam
+++ b/httpaf-lwt-unix.opam
@@ -1,3 +1,4 @@
+version: "0.6.4"
 opam-version: "2.0"
 name: "httpaf-lwt-unix"
 maintainer: "Spiros Eliopoulos <spiros@inhabitedtype.com>"
diff --git a/httpaf.opam b/httpaf.opam
index e52f2577..61d70916 100644
--- a/httpaf.opam
+++ b/httpaf.opam
@@ -1,3 +1,4 @@
+version: "0.6.4"
 opam-version: "2.0"
 maintainer: "Spiros Eliopoulos <spiros@inhabitedtype.com>"
 authors: [ "Spiros Eliopoulos <spiros@inhabitedtype.com>" ]