diff --git a/aws-gen.opam b/aws-gen.opam
index 6864d6cf1..49f1561ac 100644
--- a/aws-gen.opam
+++ b/aws-gen.opam
@@ -18,7 +18,7 @@ depends: [
   "yojson" {>= "2.0"}
   "base-unix"
   "cmdliner" {>= "1.1.0"}
-  "fmt"
+  "fmt" {>= "0.9.0"}
   "ocaml-compiler-libs" {>= "0.11.0" }
   "ocamlgraph"
   "dune" {>= "2.7"}