diff --git a/infer/src/checkers/impurityDomain.ml b/infer/src/checkers/impurityDomain.ml
index a7a27fe41..e8fd4437c 100644
--- a/infer/src/checkers/impurityDomain.ml
+++ b/infer/src/checkers/impurityDomain.ml
@@ -58,7 +58,7 @@ let add_to_errlog ~nesting ~str ModifiedVar.{var; trace_list} errlog =
         aux ~nesting:(nesting + 1)
           ( Errlog.make_trace_element nesting location
               (F.asprintf "%s '%a' is modified when calling %a at %a" str Var.pp var
-                 PulseDomain.describe_call_event f Location.pp location)
+                 PulseDomain.CallEvent.describe f Location.pp location)
               []
           :: rev_errlog )
           (WrittenTo action)
diff --git a/infer/src/pulse/PulseDiagnostic.ml b/infer/src/pulse/PulseDiagnostic.ml
index 1387f61a6..cc33cc9be 100644
--- a/infer/src/pulse/PulseDiagnostic.ml
+++ b/infer/src/pulse/PulseDiagnostic.ml
@@ -49,7 +49,7 @@ let get_message = function
             F.fprintf fmt "accessing memory that "
         | ViaCall {f; _} ->
             F.fprintf fmt "call to %a eventually accesses memory that "
-              PulseDomain.describe_call_event f
+              PulseDomain.CallEvent.describe f
       in
       let pp_invalidation_trace line fmt trace =
         match trace.PulseDomain.Trace.action with
@@ -59,7 +59,7 @@ let get_message = function
             F.fprintf fmt "%a on line %d indirectly during the call to %a"
               PulseDomain.Invalidation.describe
               (PulseDomain.InterprocAction.get_immediate action)
-              line PulseDomain.describe_call_event f
+              line PulseDomain.CallEvent.describe f
       in
       let line_of_trace trace =
         let {Location.line; _} =
diff --git a/infer/src/pulse/PulseDomain.ml b/infer/src/pulse/PulseDomain.ml
index 467a1b9c2..4ddc2d57c 100644
--- a/infer/src/pulse/PulseDomain.ml
+++ b/infer/src/pulse/PulseDomain.ml
@@ -10,29 +10,31 @@ module L = Logging
 
 (* {2 Abstract domain description } *)
 
-type call_event =
-  | Call of Typ.Procname.t
-  | Model of string
-  | SkippedKnownCall of Typ.Procname.t
-  | SkippedUnknownCall of Exp.t
-[@@deriving compare]
-
-let pp_call_event_config ~verbose fmt =
-  let pp_proc_name = if verbose then Typ.Procname.pp else Typ.Procname.describe in
-  function
-  | Call proc_name ->
-      F.fprintf fmt "`%a`" pp_proc_name proc_name
-  | Model model ->
-      F.fprintf fmt "`%s` (modelled)" model
-  | SkippedKnownCall proc_name ->
-      F.fprintf fmt "function `%a` with no summary" pp_proc_name proc_name
-  | SkippedUnknownCall call_exp ->
-      F.fprintf fmt "unresolved call expression `%a`" Exp.pp call_exp
-
-
-let pp_call_event = pp_call_event_config ~verbose:true
-
-let describe_call_event = pp_call_event_config ~verbose:false
+module CallEvent = struct
+  type t =
+    | Call of Typ.Procname.t
+    | Model of string
+    | SkippedKnownCall of Typ.Procname.t
+    | SkippedUnknownCall of Exp.t
+  [@@deriving compare]
+
+  let pp_config ~verbose fmt =
+    let pp_proc_name = if verbose then Typ.Procname.pp else Typ.Procname.describe in
+    function
+    | Call proc_name ->
+        F.fprintf fmt "`%a`" pp_proc_name proc_name
+    | Model model ->
+        F.fprintf fmt "`%s` (modelled)" model
+    | SkippedKnownCall proc_name ->
+        F.fprintf fmt "function `%a` with no summary" pp_proc_name proc_name
+    | SkippedUnknownCall call_exp ->
+        F.fprintf fmt "unresolved call expression `%a`" Exp.pp call_exp
+
+
+  let pp = pp_config ~verbose:true
+
+  let describe = pp_config ~verbose:false
+end
 
 module Invalidation = struct
   type std_vector_function =
@@ -125,7 +127,7 @@ module ValueHistory = struct
     | CppTemporaryCreated of Location.t
     | Assignment of {location: Location.t}
     | Capture of {captured_as: Pvar.t; location: Location.t}
-    | Call of {f: call_event; location: Location.t}
+    | Call of {f: CallEvent.t; location: Location.t}
   [@@deriving compare]
 
   let pp_event_no_location fmt = function
@@ -138,7 +140,7 @@ module ValueHistory = struct
     | Assignment _ ->
         F.pp_print_string fmt "assigned"
     | Call {f; location= _} ->
-        F.fprintf fmt "returned from call to %a" pp_call_event f
+        F.fprintf fmt "returned from call to %a" CallEvent.pp f
 
 
   let location_of_event = function
@@ -175,7 +177,7 @@ end
 module InterprocAction = struct
   type 'a t =
     | Immediate of {imm: 'a; location: Location.t}
-    | ViaCall of {action: 'a t; f: call_event; location: Location.t}
+    | ViaCall of {action: 'a t; f: CallEvent.t; location: Location.t}
   [@@deriving compare]
 
   let dummy = Immediate {imm= (); location= Location.dummy}
@@ -191,7 +193,7 @@ module InterprocAction = struct
     | Immediate {imm; _} ->
         pp_immediate fmt imm
     | ViaCall {f; action; _} ->
-        F.fprintf fmt "%a in call to %a" pp_immediate (get_immediate action) pp_call_event f
+        F.fprintf fmt "%a in call to %a" pp_immediate (get_immediate action) CallEvent.pp f
 
 
   let add_to_errlog ~nesting pp_immediate action errlog =
@@ -206,7 +208,7 @@ module InterprocAction = struct
       | ViaCall {action; f; location} ->
           aux ~nesting:(nesting + 1)
             ( Errlog.make_trace_element nesting location
-                (F.asprintf "when calling %a here" pp_call_event f)
+                (F.asprintf "when calling %a here" CallEvent.pp f)
                 []
             :: rev_errlog )
             action
diff --git a/infer/src/pulse/PulseDomain.mli b/infer/src/pulse/PulseDomain.mli
index 50bb3507e..dc066c076 100644
--- a/infer/src/pulse/PulseDomain.mli
+++ b/infer/src/pulse/PulseDomain.mli
@@ -8,13 +8,15 @@
 open! IStd
 module F = Format
 
-type call_event =
-  | Call of Typ.Procname.t  (** known function with summary *)
-  | Model of string  (** hardcoded model *)
-  | SkippedKnownCall of Typ.Procname.t  (** known function without summary *)
-  | SkippedUnknownCall of Exp.t  (** couldn't link the expression to a proc name *)
+module CallEvent : sig
+  type t =
+    | Call of Typ.Procname.t  (** known function with summary *)
+    | Model of string  (** hardcoded model *)
+    | SkippedKnownCall of Typ.Procname.t  (** known function without summary *)
+    | SkippedUnknownCall of Exp.t  (** couldn't link the expression to a proc name *)
 
-val describe_call_event : F.formatter -> call_event -> unit
+  val describe : F.formatter -> t -> unit
+end
 
 module Invalidation : sig
   type std_vector_function =
@@ -49,7 +51,7 @@ module ValueHistory : sig
     | CppTemporaryCreated of Location.t
     | Assignment of {location: Location.t}
     | Capture of {captured_as: Pvar.t; location: Location.t}
-    | Call of {f: call_event; location: Location.t}
+    | Call of {f: CallEvent.t; location: Location.t}
 
   type t = event list [@@deriving compare]
 
@@ -60,7 +62,7 @@ end
 module InterprocAction : sig
   type 'a t =
     | Immediate of {imm: 'a; location: Location.t}
-    | ViaCall of {action: 'a t; f: call_event; location: Location.t}
+    | ViaCall of {action: 'a t; f: CallEvent.t; location: Location.t}
   [@@deriving compare]
 
   val get_immediate : 'a t -> 'a
diff --git a/infer/src/pulse/PulseModels.ml b/infer/src/pulse/PulseModels.ml
index 537793dd1..1f8f7f59f 100644
--- a/infer/src/pulse/PulseModels.ml
+++ b/infer/src/pulse/PulseModels.ml
@@ -106,7 +106,7 @@ module StdBasicString = struct
 
   let destructor : model =
    fun ~caller_summary:_ location ~ret:(ret_id, _) ~actuals astate ->
-    let model = PulseDomain.Model "std::basic_string::~basic_string()" in
+    let model = PulseDomain.CallEvent.Model "std::basic_string::~basic_string()" in
     let call_event = PulseDomain.ValueHistory.Call {f= model; location} in
     match actuals with
     | [(this_hist, _)] ->