diff --git a/dune-project b/dune-project
index f9337290c30ca34e61a7e862f80d62c516894fd2..31a7429fccfa19d39e363f0f7fae4b6ca6729879 100644
--- a/dune-project
+++ b/dune-project
@@ -1 +1 @@
-(lang dune 1.4)
+(lang dune 1.3)
diff --git a/fix.opam b/fix.opam
index 53c83d97bc187a8c40879525fdf8d3b820444291..70886a483ec5854042386a7544ecfed7be82b9c6 100644
--- a/fix.opam
+++ b/fix.opam
@@ -12,6 +12,6 @@ build: [
 ]
 depends: [
   "ocaml" { >= "4.03" }
-  "dune" {build}
+  "dune" { build & >= "1.3" }
 ]
 synopsis: "Facilities for memoization and fixed points"