diff --git a/CHANGES.md b/CHANGES.md
index 3175bf6e..23f0bf76 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -18,6 +18,8 @@ Unreleased
   ([#110](https://github.com/anmonteiro/piaf/pull/110))
 - openssl: set the client verify callback
   ([#112](https://github.com/anmonteiro/piaf/pull/112))
+- Piaf.Response: add `or_internal_error`
+  ([#120](https://github.com/anmonteiro/piaf/pull/120))
 
 0.1.0 2021-02-03
 --------------
diff --git a/flake.lock b/flake.lock
index 5d066115..b0ecf1d5 100644
--- a/flake.lock
+++ b/flake.lock
@@ -35,11 +35,11 @@
         "flake-utils": "flake-utils_2"
       },
       "locked": {
-        "lastModified": 1646336317,
-        "narHash": "sha256-tp+yu3UGWQx+nzmfVy9R/Uxgp7aEL5unvefVaL0CQPI=",
+        "lastModified": 1646447780,
+        "narHash": "sha256-y9diaTU+y5WnovGTlhO3v5VrvN87Oa79KE3c/hVIxaA=",
         "owner": "anmonteiro",
         "repo": "nix-overlays",
-        "rev": "b59a2c4dc6f08b583fc3777c49677577b4e1542b",
+        "rev": "8bc4e7e5f4d7579d5875ec1c11f5f20bb632b1fc",
         "type": "github"
       },
       "original": {
diff --git a/lib/piaf.mli b/lib/piaf.mli
index 08294018..e467ebff 100644
--- a/lib/piaf.mli
+++ b/lib/piaf.mli
@@ -509,6 +509,7 @@ module Response : sig
     -> string
     -> (t, Error.t) Lwt_result.t
 
+  val or_internal_error : (t, Error.t) Result.t -> t
   val persistent_connection : t -> bool
   val pp_hum : Format.formatter -> t -> unit [@@ocaml.toplevel_printer]
 end
diff --git a/lib/response.ml b/lib/response.ml
index 65da7470..25f2927a 100644
--- a/lib/response.ml
+++ b/lib/response.ml
@@ -140,6 +140,12 @@ let of_h2 ?(body = Body.empty) response =
   let headers = H2.Headers.remove headers ":status" in
   { status; headers; version = { major = 2; minor = 0 }; body }
 
+let or_internal_error = function
+  | Ok r -> r
+  | Error err ->
+    let body = Format.asprintf "Internal Server Error: %a" Error.pp_hum err in
+    of_string ~body `Internal_server_error
+
 let persistent_connection { version; headers; _ } =
   Message.persistent_connection version headers