diff --git a/vif.opam b/vif.opam
index ab8498d..8cdc04f 100644
--- a/vif.opam
+++ b/vif.opam
@@ -17,6 +17,7 @@ depends: [
   "httpcats"
   "tyre"
   "mirage-crypto-rng-miou-unix"
+  "hmap"
 ]
 conflicts: [ "result" {< "1.5"} ]
 build: [