diff --git a/infer/src/backend/InferPrint.ml b/infer/src/backend/InferPrint.ml
index 7c1223251..3b7c5f66b 100644
--- a/infer/src/backend/InferPrint.ml
+++ b/infer/src/backend/InferPrint.ml
@@ -679,37 +679,6 @@ module PreconditionStats = struct
     L.result "Procedures with data constraints: %d@." !nr_dataconstraints
 end
 
-(** Wrapper of an issue that compares all parts except the procname *)
-module Issue = struct
-  type err_data_ = Errlog.err_data
-
-  (* no derived compare for err_data; just compare the locations *)
-  let compare_err_data_ (err_data1 : Errlog.err_data) (err_data2 : Errlog.err_data) =
-    Location.compare err_data1.loc err_data2.loc
-
-
-  type proc_name_ = Typ.Procname.t
-
-  (* ignore proc name *)
-  let compare_proc_name_ _ _ = 0
-
-  type t =
-    {proc_name: proc_name_; proc_location: Location.t; err_key: Errlog.err_key; err_data: err_data_}
-  [@@deriving compare]
-
-  (* If two issues are identical except for their procnames, they are probably duplicate reports on
-     two different instantiations of the same template. We don't want to spam users by reporting
-     identical warning on the same line. Accomplish this by sorting without regard to procname, then
-     de-duplicating. *)
-  let sort_filter_issues issues =
-    let issues' = List.dedup_and_sort ~compare issues in
-    ( if Config.developer_mode then
-      let num_pruned_issues = List.length issues - List.length issues' in
-      if num_pruned_issues > 0 then
-        L.user_warning "Note: pruned %d duplicate issues@\n" num_pruned_issues ) ;
-    issues'
-end
-
 let error_filter filters proc_name file error_name =
   (Config.write_html || not (IssueType.(equal skip_function) error_name))
   && filters.Inferconfig.path_filter file
diff --git a/infer/src/backend/Issue.ml b/infer/src/backend/Issue.ml
new file mode 100644
index 000000000..a8bd57181
--- /dev/null
+++ b/infer/src/backend/Issue.ml
@@ -0,0 +1,38 @@
+(*
+ * Copyright (c) 2016-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *)
+
+open! IStd
+module L = Logging
+
+(** Wrapper of an issue that compares all parts except the procname *)
+type err_data_ = Errlog.err_data
+
+(* no derived compare for err_data; just compare the locations *)
+let compare_err_data_ (err_data1 : Errlog.err_data) (err_data2 : Errlog.err_data) =
+  Location.compare err_data1.loc err_data2.loc
+
+
+type proc_name_ = Typ.Procname.t
+
+(* ignore proc name *)
+let compare_proc_name_ _ _ = 0
+
+type t =
+  {proc_name: proc_name_; proc_location: Location.t; err_key: Errlog.err_key; err_data: err_data_}
+[@@deriving compare]
+
+(* If two issues are identical except for their procnames, they are probably duplicate reports on
+     two different instantiations of the same template. We don't want to spam users by reporting
+     identical warning on the same line. Accomplish this by sorting without regard to procname, then
+     de-duplicating. *)
+let sort_filter_issues issues =
+  let issues' = List.dedup_and_sort ~compare issues in
+  ( if Config.developer_mode then
+    let num_pruned_issues = List.length issues - List.length issues' in
+    if num_pruned_issues > 0 then
+      L.user_warning "Note: pruned %d duplicate issues@\n" num_pruned_issues ) ;
+  issues'
diff --git a/infer/src/backend/Issue.mli b/infer/src/backend/Issue.mli
new file mode 100644
index 000000000..b4ce44a4a
--- /dev/null
+++ b/infer/src/backend/Issue.mli
@@ -0,0 +1,17 @@
+(*
+ * Copyright (c) 2016-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *)
+
+open! IStd
+
+type err_data_ = Errlog.err_data
+
+type proc_name_ = Typ.Procname.t
+
+type t =
+  {proc_name: proc_name_; proc_location: Location.t; err_key: Errlog.err_key; err_data: err_data_}
+
+val sort_filter_issues : t list -> t list