diff --git a/mirage-crypto-rng-miou-unix.opam b/mirage-crypto-rng-miou-unix.opam
index 4a04a259..4f57d0f9 100644
--- a/mirage-crypto-rng-miou-unix.opam
+++ b/mirage-crypto-rng-miou-unix.opam
@@ -19,7 +19,7 @@ depends: [
   "logs"
   "mirage-crypto-rng" {=version}
   "duration"
-  "mtime"
+  "mtime" {>= "1.0.0"}
   "digestif" {>= "1.2.0"}
   "ohex" {with-test & >= "0.2.0"}
 ]