diff --git a/src/core/server.ml b/src/core/server.ml
index ded29518..2ddfd50c 100644
--- a/src/core/server.ml
+++ b/src/core/server.ml
@@ -2,6 +2,8 @@ open Common_
 
 type resp_error = Response_code.t * string
 
+exception Bad_req = Common_.Bad_req
+
 module Middleware = struct
   type handler = IO.Input.t Request.t -> resp:(Response.t -> unit) -> unit
   type t = handler -> handler
diff --git a/src/core/server.mli b/src/core/server.mli
index ee908244..05ef6392 100644
--- a/src/core/server.mli
+++ b/src/core/server.mli
@@ -8,6 +8,9 @@
     @since 0.13
 *)
 
+exception Bad_req of int * string
+(** Exception raised to exit request handlers with a code+error message *)
+
 (** {2 Middlewares}
 
     A middleware can be inserted in a handler to modify or observe