diff --git a/pkgs/development/ocaml-modules/eio/default.nix b/pkgs/development/ocaml-modules/eio/default.nix
index dcffdd7dbe48..0eafead13cf1 100644
--- a/pkgs/development/ocaml-modules/eio/default.nix
+++ b/pkgs/development/ocaml-modules/eio/default.nix
@@ -1,6 +1,6 @@
 { lib
 , ocaml
-, version ? if lib.versionAtLeast ocaml.version "5.1" then "0.15" else "0.12"
+, version ? if lib.versionAtLeast ocaml.version "5.1" then "1.0" else "0.12"
 , buildDunePackage
 , bigstringaf
 , cstruct
@@ -24,9 +24,9 @@ let
       minimalOCamlVersion = "5.0";
       hash = "sha256-2EhHzoX/t4ZBSWrSS+PGq1zCxohc7a1q4lfsrFnZJqA=";
     };
-    "0.15" = {
+    "1.0" = {
       minimalOCamlVersion = "5.1";
-      hash = "sha256-gH7O8zfdqEmwXT29F6ko5vXGNudusV4iE2Z8kRJ3GKc=";
+      hash = "sha256-2iYNnaOLPd6fMWZSogsTomHPkLhaJJisZpt9Vk5hlC0=";
     };
   }."${version}";
 in