diff --git a/packages/caldav.0.2.99~dev/opam b/packages/caldav.0.2.99~dev/opam
index 92b15de..5202ae3 100644
--- a/packages/caldav.0.2.99~dev/opam
+++ b/packages/caldav.0.2.99~dev/opam
@@ -31,7 +31,7 @@ depends: [
   "fmt" {>= "0.8.7"}
   "mirage-kv" {>= "6.0.0"}
   "mirage-clock" {>= "2.0.0"}
-  "mirage-random" {>= "2.0.0"}
+  "mirage-random" {>= "2.0.0" & < "4.0.0"}
   "ppx_deriving" {>= "4.3"}
   "lwt" {>= "4.0"}
   "ptime" {>= "0.8.5"}
@@ -48,7 +48,7 @@ depends: [
   "sexplib" {>= "v0.12.0"}
   "ppx_sexp_conv" {>= "v0.12.0"}
   "logs" {>= "0.6.3"}
-  "hex" {>= "1.4.0"}
+  "ohex" {>= "0.2.0"}
   "metrics"
   "re" {>= "1.7.2"}
   #from webmachine