diff --git a/pkgs/development/ocaml-modules/uri/default.nix b/pkgs/development/ocaml-modules/uri/default.nix
index ae41c872960..f08ee7fc2fc 100644
--- a/pkgs/development/ocaml-modules/uri/default.nix
+++ b/pkgs/development/ocaml-modules/uri/default.nix
@@ -4,7 +4,9 @@
 , sexplib_p4
 }:
 
-assert stdenv.lib.versionAtLeast ocaml.version "4";
+if !stdenv.lib.versionAtLeast ocaml.version "4"
+|| legacyVersion && stdenv.lib.versionAtLeast ocaml.version "4.03"
+then throw "uri${stdenv.lib.optionalString legacyVersion "_p4"} is not available for OCaml ${ocaml.version}" else
 
 with
   if legacyVersion