diff --git a/infer/src/checkers/Sink.ml b/infer/src/checkers/Sink.ml
index 9fd47b262..ebd6969de 100644
--- a/infer/src/checkers/Sink.ml
+++ b/infer/src/checkers/Sink.ml
@@ -15,23 +15,15 @@ module L = Logging
 module type Kind = sig
   include TraceElem.Kind
 
-  (** return the parameter index and sink kind for the given call site with the given actuals *)
-  val get : Typ.Procname.t -> HilExp.t list -> Tenv.t -> (t * int) list
+  val get : Typ.Procname.t -> HilExp.t list -> Tenv.t -> (t * IntSet.t) option
 end
 
 module type S = sig
   include TraceElem.S
 
-  type parameter =
-    {
-      sink : t;
-      (** sink type of the parameter *)
-      index : int;
-      (** index of the parameter *)
-    }
-
-  (** return the parameter index and sink kind for the given call site with the given actuals *)
-  val get : CallSite.t -> HilExp.t list -> Tenv.t -> parameter list
+  val get : CallSite.t -> HilExp.t list -> Tenv.t -> t option
+
+  val indexes : t -> IntSet.t
 end
 
 module Make (Kind : Kind) = struct
@@ -41,32 +33,25 @@ module Make (Kind : Kind) = struct
     {
       kind : Kind.t;
       site : CallSite.t;
+      indexes : IntSet.t;
     } [@@deriving compare]
 
-  type parameter =
-    {
-      sink : t;
-      (** sink type of the parameter *)
-      index : int;
-      (** index of the parameter *)
-    }
-
   let kind t =
     t.kind
 
   let call_site t =
     t.site
 
-  let make kind site =
-    { kind; site; }
+  let indexes t =
+    t.indexes
 
-  let make_sink_param sink index =
-    { sink; index; }
+  let make ?(indexes=IntSet.empty) kind site =
+    { kind; site; indexes; }
 
   let get site actuals tenv =
-    List.map
-      ~f:(fun (kind, index) -> make_sink_param (make kind site) index)
-      (Kind.get (CallSite.pname site) actuals tenv)
+    match Kind.get (CallSite.pname site) actuals tenv with
+    | Some (kind, indexes) -> Some { kind; site; indexes; }
+    | None -> None
 
   let with_callsite t callee_site =
     { t with site = callee_site; }
diff --git a/infer/src/checkers/Sink.mli b/infer/src/checkers/Sink.mli
index 2f9c2800a..5e985e823 100644
--- a/infer/src/checkers/Sink.mli
+++ b/infer/src/checkers/Sink.mli
@@ -12,23 +12,18 @@ open! IStd
 module type Kind = sig
   include TraceElem.Kind
 
-  (** return the parameter index and sink kind for the given call site with the given actuals *)
-  val get : Typ.Procname.t -> HilExp.t list -> Tenv.t -> (t * int) list
+  (** return Some kind if the given procname/actuals are a sink, None otherwise *)
+  val get : Typ.Procname.t -> HilExp.t list -> Tenv.t -> (t * IntSet.t)  option
 end
 
 module type S = sig
   include TraceElem.S
 
-  type parameter =
-    {
-      sink : t;
-      (** sink type of the parameter *)
-      index : int;
-      (** index of the parameter *)
-    }
+  (** return Some sink if the given call site/actuals are a sink, None otherwise *)
+  val get : CallSite.t -> HilExp.t list -> Tenv.t -> t option
 
-  (** return the parameter index and sink kind for the given call site with the given actuals *)
-  val get : CallSite.t -> HilExp.t list -> Tenv.t -> parameter list
+  (** return the indexes where taint can flow into the sink *)
+  val indexes : t -> IntSet.t
 end
 
 module Make (Kind : Kind) : S with module Kind = Kind
diff --git a/infer/src/checkers/SinkTrace.ml b/infer/src/checkers/SinkTrace.ml
index bdaac9e87..ab305bacc 100644
--- a/infer/src/checkers/SinkTrace.ml
+++ b/infer/src/checkers/SinkTrace.ml
@@ -32,9 +32,9 @@ end
 
 module MakeSink(TraceElem : TraceElem.S) = struct
   include TraceElem
-  type parameter = { sink : t; index : int; }
 
-  let get _ _ _ = []
+  let get _ _ _ = None
+  let indexes _ = IntSet.empty
 end
 
 module Make (TraceElem : TraceElem.S) = struct
diff --git a/infer/src/checkers/SiofTrace.ml b/infer/src/checkers/SiofTrace.ml
index bf6f06ba0..2f3904bfd 100644
--- a/infer/src/checkers/SiofTrace.ml
+++ b/infer/src/checkers/SiofTrace.ml
@@ -35,7 +35,7 @@ module TraceElem = struct
 
   let kind { kind; } = snd kind
 
-  let make kind site = { kind = (`Call, kind); site; }
+  let make ?indexes:_ kind site = { kind = (`Call, kind); site; }
 
   let with_callsite { kind=(_, kind); } site = { kind=(`Call, kind); site; }
 
diff --git a/infer/src/checkers/Source.ml b/infer/src/checkers/Source.ml
index df4dc1e93..98e9d1053 100644
--- a/infer/src/checkers/Source.ml
+++ b/infer/src/checkers/Source.ml
@@ -85,7 +85,7 @@ module Make (Kind : Kind) = struct
     | Normal kind -> kind
     | Footprint _ -> Kind.unknown
 
-  let make kind site =
+  let make ?indexes:_ kind site =
     { site; kind = Normal kind; }
 
   let make_footprint ap pdesc =
@@ -135,7 +135,7 @@ module Dummy = struct
 
   let kind t = t
 
-  let make kind _ = kind
+  let make ?indexes:_ kind _ = kind
 
   let pp _ () = ()
 
diff --git a/infer/src/checkers/ThreadSafetyDomain.ml b/infer/src/checkers/ThreadSafetyDomain.ml
index dec63da68..6bbd25804 100644
--- a/infer/src/checkers/ThreadSafetyDomain.ml
+++ b/infer/src/checkers/ThreadSafetyDomain.ml
@@ -48,7 +48,7 @@ module TraceElem = struct
 
   let kind { kind; } = kind
 
-  let make kind site = { kind; site; }
+  let make ?indexes:_ kind site = { kind; site; }
 
   let with_callsite t site = { t with site; }
 
diff --git a/infer/src/checkers/TraceElem.ml b/infer/src/checkers/TraceElem.ml
index d1598fd3b..70f976e52 100644
--- a/infer/src/checkers/TraceElem.ml
+++ b/infer/src/checkers/TraceElem.ml
@@ -25,7 +25,7 @@ module type S = sig
   val call_site : t -> CallSite.t
   val kind : t -> Kind.t
 
-  val make : Kind.t -> CallSite.t -> t
+  val make : ?indexes:IntSet.t -> Kind.t -> CallSite.t -> t
   val with_callsite : t -> CallSite.t -> t
 
   val pp : F.formatter -> t -> unit
diff --git a/infer/src/quandary/ClangTrace.ml b/infer/src/quandary/ClangTrace.ml
index 9663b0936..a4019eb19 100644
--- a/infer/src/quandary/ClangTrace.ml
+++ b/infer/src/quandary/ClangTrace.ml
@@ -128,10 +128,10 @@ module SinkKind = struct
 
   (* taint the nth parameter (0-indexed) *)
   let taint_nth n kind =
-    [kind, n]
+    Some (kind, IntSet.singleton n)
 
   let taint_all actuals kind =
-    List.mapi ~f:(fun actual_num _ -> kind, actual_num) actuals
+    Some (kind, IntSet.of_list (List.mapi ~f:(fun actual_num _ -> actual_num) actuals))
 
   (* return Some(sink kind) if [procedure_name] is in the list of externally specified sinks *)
   let get_external_sink pname actuals =
@@ -143,10 +143,10 @@ module SinkKind = struct
             let kind = of_string kind in
             try
               let n = int_of_string index in
-              Some (taint_nth n kind)
+              taint_nth n kind
             with Failure _ ->
               (* couldn't parse the index, just taint everything *)
-              Some (taint_all actuals kind)
+              taint_all actuals kind
           else
             None)
       external_sinks
@@ -154,7 +154,7 @@ module SinkKind = struct
   let get pname actuals _ =
     match pname with
     | Typ.Procname.ObjC_Cpp _ ->
-        Option.value (get_external_sink pname actuals) ~default:[]
+        get_external_sink pname actuals
     | Typ.Procname.C _ ->
         begin
           match Typ.Procname.to_string pname with
@@ -163,12 +163,12 @@ module SinkKind = struct
           | "brk" | "calloc" | "malloc" | "realloc" | "sbrk" ->
               taint_all actuals Allocation
           | _ ->
-              Option.value (get_external_sink pname actuals) ~default:[]
+              get_external_sink pname actuals
         end
     | Typ.Procname.Block _ ->
-        []
+        None
     | pname when BuiltinDecl.is_declared pname ->
-        []
+        None
     | pname ->
         failwithf "Non-C++ procname %a in C++ analysis@." Typ.Procname.pp pname
 
diff --git a/infer/src/quandary/JavaTrace.ml b/infer/src/quandary/JavaTrace.ml
index 80681e76c..cc1b0ae64 100644
--- a/infer/src/quandary/JavaTrace.ml
+++ b/infer/src/quandary/JavaTrace.ml
@@ -218,13 +218,14 @@ module SinkKind = struct
         if Typ.Procname.java_is_static pname || taint_this
         then actuals, 0
         else List.tl_exn actuals, 1 in
-      List.mapi
-        ~f:(fun param_num _ -> kind, param_num + offset)
-        actuals_to_taint in
+      let indexes =
+        IntSet.of_list (List.mapi ~f:(fun param_num _ -> param_num + offset) actuals_to_taint) in
+      Some (kind, indexes) in
+
     (* taint the nth non-"this" parameter (0-indexed) *)
     let taint_nth n kind =
       let first_index = if Typ.Procname.java_is_static pname then n else n + 1 in
-      [kind, first_index] in
+      Some (kind, IntSet.singleton first_index) in
     match pname with
     | Typ.Procname.Java java_pname ->
         begin
@@ -237,17 +238,17 @@ module SinkKind = struct
           | "java.nio.file.Paths", "get" ->
               taint_all CreateFile
           | "com.facebook.infer.builtins.InferTaint", "inferSensitiveSink" ->
-              [Other, 0]
+              taint_nth 0 Other
           | class_name, method_name ->
               let taint_matching_supertype typename _ =
                 match Typ.Name.name typename, method_name with
                 | "android.app.Activity",
                   ("startActivityFromChild" | "startActivityFromFragment") ->
-                    Some (taint_nth 1 StartComponent)
+                    taint_nth 1 StartComponent
                 | "android.app.Activity", "startIntentSenderForResult"  ->
-                    Some (taint_nth 2 StartComponent)
+                    taint_nth 2 StartComponent
                 | "android.app.Activity", "startIntentSenderFromChild"  ->
-                    Some (taint_nth 3 StartComponent)
+                    taint_nth 3 StartComponent
                 | "android.content.Context",
                   ("bindService" |
                    "sendBroadcast" |
@@ -265,9 +266,9 @@ module SinkKind = struct
                    "startNextMatchingActivity" |
                    "startService" |
                    "stopService") ->
-                    Some (taint_nth 0 StartComponent)
+                    taint_nth 0 StartComponent
                 | "android.content.Context", "startIntentSender" ->
-                    Some (taint_nth 1 StartComponent)
+                    taint_nth 1 StartComponent
                 | "android.content.Intent",
                   ("parseUri" |
                    "getIntent" |
@@ -278,9 +279,9 @@ module SinkKind = struct
                    "setDataAndType" |
                    "setDataAndTypeAndNormalize" |
                    "setPackage") ->
-                    Some (taint_nth 0 CreateIntent)
+                    taint_nth 0 CreateIntent
                 | "android.content.Intent", "setClassName" ->
-                    Some (taint_all CreateIntent)
+                    taint_all CreateIntent
                 | "android.webkit.WebView",
                   ("evaluateJavascript" |
                    "loadData" |
@@ -288,7 +289,7 @@ module SinkKind = struct
                    "loadUrl" |
                    "postUrl" |
                    "postWebMessage") ->
-                    Some (taint_all JavaScript)
+                    taint_all JavaScript
                 | class_name, method_name ->
                     (* check the list of externally specified sinks *)
                     let procedure = class_name ^ "." ^ method_name in
@@ -299,25 +300,19 @@ module SinkKind = struct
                             let kind = of_string kind in
                             try
                               let n = int_of_string index in
-                              Some (taint_nth n kind)
+                              taint_nth n kind
                             with Failure _ ->
                               (* couldn't parse the index, just taint everything *)
-                              Some (taint_all kind)
+                              taint_all kind
                           else
                             None)
                       external_sinks in
-              begin
-                match
-                  PatternMatch.supertype_find_map_opt
-                    tenv
-                    taint_matching_supertype
-                    (Typ.Name.Java.from_string class_name) with
-                | Some sinks -> sinks
-                | None -> []
-              end
-
+              PatternMatch.supertype_find_map_opt
+                tenv
+                taint_matching_supertype
+                (Typ.Name.Java.from_string class_name)
         end
-    | pname when BuiltinDecl.is_declared pname -> []
+    | pname when BuiltinDecl.is_declared pname -> None
     | pname -> failwithf "Non-Java procname %a in Java analysis@." Typ.Procname.pp pname
 
   let pp fmt kind =
diff --git a/infer/src/quandary/TaintAnalysis.ml b/infer/src/quandary/TaintAnalysis.ml
index e4d08da4e..85ad09e53 100644
--- a/infer/src/quandary/TaintAnalysis.ml
+++ b/infer/src/quandary/TaintAnalysis.ml
@@ -158,16 +158,16 @@ module Make (TaintSpecification : TaintSpec.S) = struct
 
       List.iter ~f:report_error (TraceDomain.get_reportable_paths ~cur_site trace ~trace_of_pname)
 
-    let add_sinks sinks actuals access_tree proc_data callee_site =
+    let add_sink sink actuals access_tree proc_data callee_site =
       (* add [sink] to the trace associated with the [formal_index]th actual *)
-      let add_sink_to_actual access_tree_acc (sink_param : TraceDomain.Sink.parameter) =
-        match List.nth_exn actuals sink_param.index with
+      let add_sink_to_actual sink_index access_tree_acc =
+        match List.nth_exn actuals sink_index with
         | HilExp.AccessPath actual_ap_raw ->
             let actual_ap = AccessPath.Abstracted actual_ap_raw in
             begin
               match access_path_get_node actual_ap access_tree_acc proc_data with
               | Some (actual_trace, _) ->
-                  let actual_trace' = TraceDomain.add_sink sink_param.sink actual_trace in
+                  let actual_trace' = TraceDomain.add_sink sink actual_trace in
                   report_trace actual_trace' callee_site proc_data;
                   TaintDomain.add_trace actual_ap actual_trace' access_tree_acc
               | None ->
@@ -175,7 +175,7 @@ module Make (TaintSpecification : TaintSpec.S) = struct
             end
         | _ ->
             access_tree_acc in
-      List.fold ~f:add_sink_to_actual ~init:access_tree sinks
+      IntSet.fold add_sink_to_actual (TraceDomain.Sink.indexes sink) access_tree
 
     let apply_summary
         ret_opt
@@ -382,10 +382,11 @@ module Make (TaintSpecification : TaintSpec.S) = struct
           let analyze_call astate_acc callee_pname =
             let call_site = CallSite.make callee_pname callee_loc in
 
-            let sinks = TraceDomain.Sink.get call_site actuals proc_data.ProcData.tenv in
-            let astate_with_sink = match sinks with
-              | [] -> astate
-              | sinks -> add_sinks sinks actuals astate proc_data call_site in
+            let sink = TraceDomain.Sink.get call_site actuals proc_data.ProcData.tenv in
+            let astate_with_sink =
+              match sink with
+              | Some sink -> add_sink sink actuals astate proc_data call_site
+              | None -> astate in
             let source = TraceDomain.Source.get call_site proc_data.tenv in
             let astate_with_source =
               match source with
@@ -400,7 +401,7 @@ module Make (TaintSpecification : TaintSpec.S) = struct
                   astate_with_sink in
 
             let astate_with_summary =
-              if sinks <> [] || Option.is_some source
+              if Option.is_some source || Option.is_some sink
               then
                 (* don't use a summary for a procedure that is a direct source or sink *)
                 astate_with_source
diff --git a/infer/src/unit/TaintTests.ml b/infer/src/unit/TaintTests.ml
index 0c60fa2fa..1266664b1 100644
--- a/infer/src/unit/TaintTests.ml
+++ b/infer/src/unit/TaintTests.ml
@@ -32,8 +32,10 @@ module MockTrace = Trace.Make(struct
 
         let get pname _ _ =
           if String.is_prefix ~prefix:"SINK" (Typ.Procname.to_string pname)
-          then [CallSite.make pname Location.dummy, 0]
-          else []
+          then Some (CallSite.make pname Location.dummy, IntSet.singleton 0)
+          else None
+
+        let indexes _ = IntSet.empty
       end)
 
     let should_report _ _ = false
diff --git a/infer/src/unit/TraceTests.ml b/infer/src/unit/TraceTests.ml
index ddb7fc8be..01b3ee1bb 100644
--- a/infer/src/unit/TraceTests.ml
+++ b/infer/src/unit/TraceTests.ml
@@ -26,7 +26,7 @@ module MockTraceElem = struct
 
   let kind t = t
 
-  let make kind _ = kind
+  let make ?indexes:_ kind _ = kind
 
   let pp fmt = function
     | Kind1 -> F.fprintf fmt "Kind1"
@@ -67,6 +67,8 @@ module MockSink = struct
 
   let get _ = assert false
 
+  let indexes _ = IntSet.empty
+
   let equal = [%compare.equal : t]
 end