diff --git a/infer/src/checkers/annotationReachability.ml b/infer/src/checkers/annotationReachability.ml
index 25c5cda110a..7d43b652f55 100644
--- a/infer/src/checkers/annotationReachability.ml
+++ b/infer/src/checkers/annotationReachability.ml
@@ -429,39 +429,22 @@ module ExpensiveAnnotationSpec = struct
     }
 end
 
-(* parse user-defined specs from .inferconfig *)
-let parse_user_defined_specs = function
-  | `List user_specs ->
-      let parse_user_spec json =
-        let open Yojson.Safe in
-        let sources = Util.member "sources" json |> Util.to_list |> List.map ~f:Util.to_string in
-        let sinks = Util.member "sinks" json |> Util.to_list |> List.map ~f:Util.to_string in
-        let sanitizers =
-          match Util.member "sanitizers" json with
-          | `List s ->
-              List.map ~f:Util.to_string s
-          | _ ->
-              L.user_warning "Expected a list of strings as sanitizers, ignoring.\n" ;
-              []
-        in
-        (sources, sinks, sanitizers)
-      in
-      List.map ~f:parse_user_spec user_specs
-  | _ ->
-      L.user_warning "Expected a list as custom annotations, ignoring.\n" ;
-      []
+type user_defined_spec =
+  {sources: string list; sinks: string list; sanitizers: string list [@yojson.default []]}
+[@@deriving of_yojson]
 
+type user_defined_specs = user_defined_spec list [@@deriving of_yojson]
 
 let annot_specs =
-  let parse_one_spec (str_src_annots, str_snk_annots, str_sanitizer_annots) =
-    List.map
-      ~f:(fun str_snk_annot ->
-        StandardAnnotationSpec.from_annotations str_src_annots str_snk_annot str_sanitizer_annots )
-      str_snk_annots
+  let make_standard_spec_from_user_spec {sources; sinks; sanitizers} =
+    List.map ~f:(fun sink -> StandardAnnotationSpec.from_annotations sources sink sanitizers) sinks
   in
   let user_defined_specs =
-    parse_user_defined_specs Config.annotation_reachability_custom_pairs
-    |> List.map ~f:parse_one_spec
+    let specs =
+      try user_defined_specs_of_yojson Config.annotation_reachability_custom_pairs
+      with _ -> L.die ExternalError "Could not parse annotation reachability custom pairs@."
+    in
+    List.map specs ~f:make_standard_spec_from_user_spec
   in
   let user_defined_specs = List.concat user_defined_specs in
   [ (Language.Clang, CxxAnnotationSpecs.from_config ())