diff --git a/src/repository/opamRepositoryConfig.ml b/src/repository/opamRepositoryConfig.ml
index c2954c1d..528fc621 100644
--- a/src/repository/opamRepositoryConfig.ml
+++ b/src/repository/opamRepositoryConfig.ml
@@ -27,31 +27,7 @@ type 'a options_fun =
   'a
 
 let default = {
-  download_tool = lazy (
-    let os = OpamStd.Sys.os () in
-    try
-      let curl = "curl", `Curl in
-      let tools =
-        match os with
-        | Darwin  -> ["wget", `Default; curl]
-        | FreeBSD -> ["fetch", `Default ; curl]
-        | OpenBSD -> ["ftp", `Default; curl]
-        | _ -> [curl; "wget", `Default]
-      in
-      let cmd, kind =
-        List.find (fun (c,_) -> OpamSystem.resolve_command c <> None) tools
-      in
-      [ CIdent cmd, None ], kind
-    with Not_found ->
-      OpamConsole.error_and_exit `Configuration_error
-        "Could not find a suitable download command. Please make sure you \
-         have %s installed, or specify a custom command through variable \
-         OPAMFETCH."
-        (match os with
-         | FreeBSD -> "fetch"
-         | OpenBSD -> "ftp"
-         | _ -> "either \"curl\" or \"wget\"")
-  );
+  download_tool = lazy ([ CIdent SUBSTITUTE_NIXOS_CURL_PATH, None ], `Curl);
   validation_hook = None;
   retries = 3;
   force_checksums = None;