diff --git a/infer/src/checkers/procCfg.ml b/infer/src/checkers/procCfg.ml
index d1398f946..37999123c 100644
--- a/infer/src/checkers/procCfg.ml
+++ b/infer/src/checkers/procCfg.ml
@@ -15,7 +15,7 @@ module F = Format
     file). Defines useful wrappers that allows us to do tricks like turn a forward cfg into a
     backward one, or view a cfg as having a single instruction per node. *)
 
-type index = Node_index | Instr_index of int
+type index = Node_index | Instr_index of int [@@deriving compare]
 
 module type Node = sig
   type t
@@ -25,7 +25,7 @@ module type Node = sig
   val id : t -> id
   val loc : t -> Location.t
   val underlying_id : t -> Procdesc.Node.id
-  val id_compare : id -> id -> int
+  val compare_id : id -> id -> int
   val pp_id : F.formatter -> id -> unit
 end
 
@@ -37,7 +37,7 @@ module DefaultNode = struct
   let id = Procdesc.Node.get_id
   let loc = Procdesc.Node.get_loc
   let underlying_id = id
-  let id_compare = Procdesc.Node.compare_id
+  let compare_id = Procdesc.Node.compare_id
   let pp_id = Procdesc.Node.pp_id
 end
 
@@ -53,16 +53,12 @@ module InstrNode = struct
 
   let loc t = Procdesc.Node.get_loc t
 
-  let index_compare index1 index2 = match index1, index2 with
-    | Node_index, Node_index -> 0
-    | Instr_index i1, Instr_index i2 -> int_compare i1 i2
-    | Node_index, Instr_index _ -> 1
-    | Instr_index _, Node_index -> -1
+  let compare_index = compare_index
 
-  let id_compare (id1, index1) (id2, index2) =
+  let compare_id (id1, index1) (id2, index2) =
     let n = Procdesc.Node.compare_id id1 id2 in
     if n <> 0 then n
-    else index_compare index1 index2
+    else compare_index index1 index2
 
   let pp_id fmt (id, index) = match index with
     | Node_index -> Procdesc.Node.pp_id fmt id
@@ -234,10 +230,10 @@ end
 
 module NodeIdMap (CFG : S) = Map.Make(struct
     type t = CFG.id
-    let compare = CFG.id_compare
+    let compare = CFG.compare_id
   end)
 
 module NodeIdSet (CFG : S) = Set.Make(struct
     type t = CFG.id
-    let compare = CFG.id_compare
+    let compare = CFG.compare_id
   end)
diff --git a/infer/src/checkers/procCfg.mli b/infer/src/checkers/procCfg.mli
index b1544e7ef..9070c83d9 100644
--- a/infer/src/checkers/procCfg.mli
+++ b/infer/src/checkers/procCfg.mli
@@ -21,7 +21,7 @@ module type Node = sig
   val id : t -> id
   val loc : t -> Location.t
   val underlying_id : t -> Procdesc.Node.id
-  val id_compare : id -> id -> int
+  val compare_id : id -> id -> int
   val pp_id : Format.formatter -> id -> unit
 end
 
diff --git a/infer/src/unit/schedulerTests.ml b/infer/src/unit/schedulerTests.ml
index 805bf58bd..988b97d4f 100644
--- a/infer/src/unit/schedulerTests.ml
+++ b/infer/src/unit/schedulerTests.ml
@@ -25,7 +25,7 @@ module MockNode = struct
   let loc _ = assert false
   let underlying_id _ = assert false
   let kind _ = Procdesc.Node.Stmt_node ""
-  let id_compare = int_compare
+  let compare_id = int_compare
   let pp_id fmt i =
     F.fprintf fmt "%i" i
 end
@@ -35,13 +35,13 @@ module MockProcCfg = struct
   include (MockNode : module type of MockNode with type t := node)
   type t = (node * node list) list
 
-  let id_compare = int_compare
+  let compare_id = int_compare
 
   let succs t n =
     try
       let node_id = id n in
       IList.find
-        (fun (node, _) -> id_compare (id node) node_id = 0)
+        (fun (node, _) -> compare_id (id node) node_id = 0)
         t
       |> snd
     with Not_found -> []
@@ -51,7 +51,7 @@ module MockProcCfg = struct
       let node_id = id n in
       IList.filter
         (fun (_, succs) ->
-           IList.exists (fun node -> id_compare (id node) node_id = 0) succs)
+           IList.exists (fun node -> compare_id (id node) node_id = 0) succs)
         t
       |> IList.map fst
     with Not_found -> []