diff --git a/infer/src/atd/jsonbug.atd b/infer/src/atd/jsonbug.atd
index b1b6d9a53..fe655f28c 100644
--- a/infer/src/atd/jsonbug.atd
+++ b/infer/src/atd/jsonbug.atd
@@ -55,6 +55,7 @@ type hum_info = {
 }
 
 type cost_item = {
+  hash : string;
   loc : loc;
   procedure_id : string;
   polynomial : string;
diff --git a/infer/src/backend/Differential.ml b/infer/src/backend/Differential.ml
index 4f495aff6..d382831d5 100644
--- a/infer/src/backend/Differential.ml
+++ b/infer/src/backend/Differential.ml
@@ -127,7 +127,8 @@ let of_reports ~(current_report : Jsonbug_t.report) ~(previous_report : Jsonbug_
     ~(current_costs : Jsonbug_t.costs_report) ~(previous_costs : Jsonbug_t.costs_report) : t =
   let to_map report =
     List.fold_left
-      ~f:(fun map issue -> Map.add_multi map ~key:issue.Jsonbug_t.hash ~data:issue)
+      ~f:(fun map (issue : Jsonbug_t.jsonbug) ->
+        Map.add_multi map ~key:issue.Jsonbug_t.hash ~data:issue )
       ~init:String.Map.empty report
   in
   let fold_aux ~key:_ ~data (left, both, right) =
diff --git a/infer/src/backend/InferPrint.ml b/infer/src/backend/InferPrint.ml
index f603af37b..aea7a2855 100644
--- a/infer/src/backend/InferPrint.ml
+++ b/infer/src/backend/InferPrint.ml
@@ -49,9 +49,9 @@ let compute_key (bug_type : string) (proc_name : Typ.Procname.t) (filename : str
   String.concat ~sep:"|" [base_filename; simple_procedure_name; bug_type]
 
 
-let compute_hash (severity : string) (bug_type : string) (proc_name : Typ.Procname.t)
-    (filename : string) (qualifier : string) =
-  let base_filename = Filename.basename filename in
+let compute_hash ~(severity : string) ~(bug_type : string) ~(proc_name : Typ.Procname.t)
+    ~(file : string) ~(qualifier : string) =
+  let base_filename = Filename.basename file in
   let hashable_procedure_name = Typ.Procname.hashable_name proc_name in
   let location_independent_qualifier =
     (* Removing the line,column, and infer temporary variable (e.g., n$67) information from the
@@ -309,7 +309,7 @@ module JsonIssuePrinter = MakeJsonListPrinter (struct
         ; bug_trace= loc_trace_to_jsonbug_record err_data.loc_trace err_key.severity
         ; node_key= Option.map ~f:Procdesc.NodeKey.to_string err_data.node_key
         ; key= compute_key bug_type proc_name file
-        ; hash= compute_hash severity bug_type proc_name file qualifier
+        ; hash= compute_hash ~severity ~bug_type ~proc_name ~file ~qualifier
         ; dotty= error_desc_to_dotty_string err_key.err_desc
         ; infer_source_loc= json_ml_loc
         ; bug_type_hum= err_key.err_name.IssueType.hum
@@ -353,11 +353,9 @@ module JsonCostsPrinter = MakeJsonListPrinter (struct
           else None
         in
         let cost_item =
-          { Jsonbug_t.loc=
-              { Jsonbug_t.file= SourceFile.to_string loc.Location.file
-              ; lnum= loc.Location.line
-              ; cnum= loc.Location.col
-              ; enum= -1 }
+          let file = SourceFile.to_string loc.Location.file in
+          { Jsonbug_t.hash= compute_hash ~severity:"" ~bug_type:"" ~proc_name ~file ~qualifier:""
+          ; loc= {file; lnum= loc.Location.line; cnum= loc.Location.col; enum= -1}
           ; procedure_id= Typ.Procname.to_string proc_name
           ; polynomial= CostDomain.BasicCost.encode post
           ; hum }
@@ -429,7 +427,7 @@ let pp_custom_of_report fmt report fields =
   List.iter ~f:(pp_custom_of_issue fmt) report
 
 
-let tests_jsonbug_compare bug1 bug2 =
+let tests_jsonbug_compare (bug1 : Jsonbug_t.jsonbug) (bug2 : Jsonbug_t.jsonbug) =
   let open Jsonbug_t in
   [%compare: string * string * int * string * Caml.Digest.t]
     (bug1.file, bug1.procedure, bug1.line - bug1.procedure_start_line, bug1.bug_type, bug1.hash)
diff --git a/infer/src/unit/DifferentialTests.ml b/infer/src/unit/DifferentialTests.ml
index cf612a0d3..834f22179 100644
--- a/infer/src/unit/DifferentialTests.ml
+++ b/infer/src/unit/DifferentialTests.ml
@@ -34,7 +34,8 @@ let test_diff_keeps_duplicated_hashes =
   let hashes_expected = 3 in
   let hashes_found =
     List.fold ~init:0
-      ~f:(fun acc i -> if String.equal i.Jsonbug_t.hash "2" then acc + 1 else acc)
+      ~f:(fun acc (i : Jsonbug_t.jsonbug) ->
+        if String.equal i.Jsonbug_t.hash "2" then acc + 1 else acc )
       diff.introduced
   in
   let pp_diff fmt (expected, actual) =
diff --git a/infer/src/unit/DifferentialTestsUtils.ml b/infer/src/unit/DifferentialTestsUtils.ml
index 619ba906e..969acdbea 100644
--- a/infer/src/unit/DifferentialTestsUtils.ml
+++ b/infer/src/unit/DifferentialTestsUtils.ml
@@ -47,6 +47,6 @@ let pp_diff_of_string_list = pp_diff_of_list ~pp:Format.pp_print_string
 let pp_diff_of_int_list = pp_diff_of_list ~pp:Format.pp_print_int
 
 (* Sort hashes to make things easier to compare *)
-let sorted_hashes_of_issues issues =
-  let hash i = i.Jsonbug_t.hash in
+let sorted_hashes_of_issues (issues : Jsonbug_t.report) =
+  let hash (i : Jsonbug_t.jsonbug) = i.Jsonbug_t.hash in
   List.sort ~compare:String.compare (List.rev_map ~f:hash issues)