diff --git a/packages/irmin-unix/irmin-unix.0.12.0/opam b/packages/irmin-unix/irmin-unix.0.12.0/opam
index 85ce38c5e6e..8dd0d9a609e 100644
--- a/packages/irmin-unix/irmin-unix.0.12.0/opam
+++ b/packages/irmin-unix/irmin-unix.0.12.0/opam
@@ -14,4 +14,12 @@ depends: [
   "irmin-watcher"
 ]
 synopsis: "Virtual package for Irmin's Unix support"
+url {
+  src:
+    "https://github.com/mirage/irmin/releases/download/0.12.0/irmin-0.12.0.tbz"
+  checksum: [
+    "sha256=d265f593391c41a13a5b7c6dab96c551575d90a63e81ae98bf4e0803910b535f"
+    "md5=04158d3e093add7b556323aeb117219c"
+  ]
+}
 flags: deprecated
diff --git a/packages/irmin-unix/irmin-unix.0.9.4/opam b/packages/irmin-unix/irmin-unix.0.9.4/opam
index c84539dffd1..509c6e2ad01 100644
--- a/packages/irmin-unix/irmin-unix.0.9.4/opam
+++ b/packages/irmin-unix/irmin-unix.0.9.4/opam
@@ -13,3 +13,10 @@ depends: [
 ]
 synopsis: "Virtual package for Irmin's Unix support"
 flags: deprecated
+url {
+  src: "https://github.com/mirage/irmin/archive/0.9.4.tar.gz"
+  checksum: [
+    "sha256=70e297ccc1087612565179b371bbec3a58c3f6fb68a7017a2d7e9271c95cf2dd"
+    "md5=c8a177fbd1984fff587a6a7223626069"
+  ]
+}
diff --git a/packages/irmin-unix/irmin-unix.0.9.9/opam b/packages/irmin-unix/irmin-unix.0.9.9/opam
index 18342ef95c0..e8239f6f269 100644
--- a/packages/irmin-unix/irmin-unix.0.9.9/opam
+++ b/packages/irmin-unix/irmin-unix.0.9.9/opam
@@ -12,3 +12,10 @@ depends: [
 ]
 synopsis: "Virtual package for Irmin's Unix support"
 flags: deprecated
+url {
+  src: "https://github.com/mirage/irmin/archive/0.9.9.tar.gz"
+  checksum: [
+    "sha256=0ecb1bf941169aff6d25708c716d8f13734865e1aaee35276bb1cf70ac9426f0"
+    "md5=ca3763989c291d96a7fc24047268a257"
+  ]
+}