diff --git a/src/core/CCFormat.ml b/src/core/CCFormat.ml
index e1ff197a..a4ac12f0 100644
--- a/src/core/CCFormat.ml
+++ b/src/core/CCFormat.ml
@@ -127,6 +127,8 @@ let hbox pp out x =
 
 let of_to_string f out x = Format.pp_print_string out (f x)
 
+let exn = of_to_string Printexc.to_string
+
 let const pp x out () = pp out x
 
 let some pp out = function
diff --git a/src/core/CCFormat.mli b/src/core/CCFormat.mli
index 3fdb0b27..f4a0198f 100644
--- a/src/core/CCFormat.mli
+++ b/src/core/CCFormat.mli
@@ -29,6 +29,10 @@ val bool : bool printer
 val float3 : float printer (* 3 digits after . *)
 val float : float printer
 
+val exn : exn printer
+(** Printer using {!Printexc.to_string}.
+    @since NEXT_RELEASE *)
+
 val newline : unit printer
 (** Force newline (see {!Format.pp_force_newline}).
     @since 1.2 *)