diff --git a/infer/src/IR/Sil.re b/infer/src/IR/Sil.re
index 3c8cd29e9..6747c09d2 100644
--- a/infer/src/IR/Sil.re
+++ b/infer/src/IR/Sil.re
@@ -37,13 +37,6 @@ let get_sentinel_func_attribute_value attr_list =>
   };
 
 
-/** Unary operations */
-type unop =
-  | Neg /** Unary minus */
-  | BNot /** Bitwise complement (~) */
-  | LNot /** Logical Not (!) */;
-
-
 /** Binary operations */
 type binop =
   | PlusA /** arithmetic + */
@@ -427,7 +420,7 @@ type dexp =
   | Ddot of dexp Ident.fieldname
   | Dpvar of Pvar.t
   | Dpvaraddr of Pvar.t
-  | Dunop of unop dexp
+  | Dunop of Unop.t dexp
   | Dunknown
   | Dretcall of dexp (list dexp) Location.t call_flags;
 
@@ -477,7 +470,7 @@ and exp =
   /** Pure variable: it is not an lvalue */
   | Var of Ident.t
   /** Unary operator with type of the result if known */
-  | UnOp of unop exp (option Typ.t)
+  | UnOp of Unop.t exp (option Typ.t)
   /** Binary operator */
   | BinOp of binop exp exp
   /** Exception */
@@ -714,19 +707,6 @@ let exp_is_this =
   | Lvar pvar => Pvar.is_this pvar
   | _ => false;
 
-let unop_compare o1 o2 =>
-  switch (o1, o2) {
-  | (Neg, Neg) => 0
-  | (Neg, _) => (-1)
-  | (_, Neg) => 1
-  | (BNot, BNot) => 0
-  | (BNot, _) => (-1)
-  | (_, BNot) => 1
-  | (LNot, LNot) => 0
-  };
-
-let unop_equal o1 o2 => unop_compare o1 o2 == 0;
-
 let binop_compare o1 o2 =>
   switch (o1, o2) {
   | (PlusA, PlusA) => 0
@@ -1062,7 +1042,7 @@ let rec exp_compare (e1: exp) (e2: exp) :int =>
   | (Var _, _) => (-1)
   | (_, Var _) => 1
   | (UnOp o1 e1 to1, UnOp o2 e2 to2) =>
-    let n = unop_compare o1 o2;
+    let n = Unop.compare o1 o2;
     if (n != 0) {
       n
     } else {
@@ -1509,14 +1489,6 @@ let text_binop =
   | PtrFld => "_ptrfld_";
 
 
-/** String representation of unary operator. */
-let str_unop =
-  fun
-  | Neg => "-"
-  | BNot => "~"
-  | LNot => "!";
-
-
 /** Pretty print a binary operator. */
 let str_binop pe binop =>
   switch pe.pe_kind {
@@ -1628,7 +1600,7 @@ let rec dexp_to_string =
         };
       ampersand ^ s
     }
-  | Dunop op de => str_unop op ^ dexp_to_string de
+  | Dunop op de => Unop.str op ^ dexp_to_string de
   | Dsizeof typ _ _ => pp_to_string (Typ.pp_full pe_text) typ
   | Dunknown => "unknown"
   | Dretcall de _ _ _ => "returned by " ^ dexp_to_string de;
@@ -1756,7 +1728,7 @@ let rec _pp_exp pe0 pp_t f e0 => {
     | Var id => (Ident.pp pe) f id
     | Const c => F.fprintf f "%a" (Const.pp pe) c
     | Cast typ e => F.fprintf f "(%a)%a" pp_t typ pp_exp e
-    | UnOp op e _ => F.fprintf f "%s%a" (str_unop op) pp_exp e
+    | UnOp op e _ => F.fprintf f "%s%a" (Unop.str op) pp_exp e
     | BinOp op (Const c) e2 when Config.smt_output => print_binop_stm_output (Const c) op e2
     | BinOp op e1 e2 => F.fprintf f "(%a %s %a)" pp_exp e1 (str_binop pe op) pp_exp e2
     | Exn e => F.fprintf f "EXN %a" pp_exp e
@@ -3663,7 +3635,7 @@ let rec exp_compare_structural e1 e2 exp_map => {
   switch (e1, e2) {
   | (Var _, Var _) => compare_exps_with_map e1 e2 exp_map
   | (UnOp o1 e1 to1, UnOp o2 e2 to2) =>
-    let n = unop_compare o1 o2;
+    let n = Unop.compare o1 o2;
     if (n != 0) {
       (n, exp_map)
     } else {
diff --git a/infer/src/IR/Sil.rei b/infer/src/IR/Sil.rei
index dd9b151bd..163bc7f29 100644
--- a/infer/src/IR/Sil.rei
+++ b/infer/src/IR/Sil.rei
@@ -26,13 +26,6 @@ type func_attribute = | FA_sentinel of int int;
 type access = | Default | Public | Private | Protected;
 
 
-/** Unary operations */
-type unop =
-  | Neg /** Unary minus */
-  | BNot /** Bitwise complement (~) */
-  | LNot /** Logical Not (!) */;
-
-
 /** Binary operations */
 type binop =
   | PlusA /** arithmetic + */
@@ -154,7 +147,7 @@ type dexp =
   | Ddot of dexp Ident.fieldname
   | Dpvar of Pvar.t
   | Dpvaraddr of Pvar.t
-  | Dunop of unop dexp
+  | Dunop of Unop.t dexp
   | Dunknown
   | Dretcall of dexp (list dexp) Location.t call_flags;
 
@@ -204,7 +197,7 @@ and exp =
   /** Pure variable: it is not an lvalue */
   | Var of Ident.t
   /** Unary operator with type of the result if known */
-  | UnOp of unop exp (option Typ.t)
+  | UnOp of Unop.t exp (option Typ.t)
   /** Binary operator */
   | BinOp of binop exp exp
   /** Exception */
@@ -489,8 +482,6 @@ let block_pvar: Pvar.t;
 /** Check if a pvar is a local pointing to a block in objc */
 let is_block_pvar: Pvar.t => bool;
 
-let unop_equal: unop => unop => bool;
-
 let binop_equal: binop => binop => bool;
 
 
@@ -621,10 +612,6 @@ let color_pre_wrapper: printenv => F.formatter => 'a => (printenv, bool);
 let color_post_wrapper: bool => printenv => F.formatter => unit;
 
 
-/** String representation of a unary operator. */
-let str_unop: unop => string;
-
-
 /** String representation of a binary operator. */
 let str_binop: printenv => binop => string;
 
diff --git a/infer/src/IR/Unop.re b/infer/src/IR/Unop.re
new file mode 100644
index 000000000..65855b81e
--- /dev/null
+++ b/infer/src/IR/Unop.re
@@ -0,0 +1,48 @@
+/*
+ * vim: set ft=rust:
+ * vim: set ft=reason:
+ *
+ * Copyright (c) 2009 - 2013 Monoidics ltd.
+ * Copyright (c) 2013 - present Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+open! Utils;
+
+
+/** The Smallfoot Intermediate Language: Unary Operators */
+let module L = Logging;
+
+let module F = Format;
+
+
+/** Unary operations */
+type t =
+  | Neg /** Unary minus */
+  | BNot /** Bitwise complement (~) */
+  | LNot /** Logical Not (!) */;
+
+let compare o1 o2 =>
+  switch (o1, o2) {
+  | (Neg, Neg) => 0
+  | (Neg, _) => (-1)
+  | (_, Neg) => 1
+  | (BNot, BNot) => 0
+  | (BNot, _) => (-1)
+  | (_, BNot) => 1
+  | (LNot, LNot) => 0
+  };
+
+let equal o1 o2 => compare o1 o2 == 0;
+
+
+/** String representation of unary operator. */
+let str =
+  fun
+  | Neg => "-"
+  | BNot => "~"
+  | LNot => "!";
diff --git a/infer/src/IR/Unop.rei b/infer/src/IR/Unop.rei
new file mode 100644
index 000000000..2f45bb1dd
--- /dev/null
+++ b/infer/src/IR/Unop.rei
@@ -0,0 +1,35 @@
+/*
+ * vim: set ft=rust:
+ * vim: set ft=reason:
+ *
+ * Copyright (c) 2009 - 2013 Monoidics ltd.
+ * Copyright (c) 2013 - present Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+open! Utils;
+
+
+/** The Smallfoot Intermediate Language: Unary Operators */
+let module L = Logging;
+
+let module F = Format;
+
+
+/** Unary operations */
+type t =
+  | Neg /** Unary minus */
+  | BNot /** Bitwise complement (~) */
+  | LNot /** Logical Not (!) */;
+
+let equal: t => t => bool;
+
+let compare: t => t => int;
+
+
+/** String representation of a unary operator. */
+let str: t => string;
diff --git a/infer/src/backend/dom.ml b/infer/src/backend/dom.ml
index 0671a8d29..7c47d2962 100644
--- a/infer/src/backend/dom.ml
+++ b/infer/src/backend/dom.ml
@@ -937,7 +937,7 @@ let rec exp_partial_join (e1: Sil.exp) (e2: Sil.exp) : Sil.exp =
         let e1'' = exp_partial_join e1 e2 in
         Sil.Cast (t1, e1'')
   | Sil.UnOp(unop1, e1, topt1), Sil.UnOp(unop2, e2, _) ->
-      if not (Sil.unop_equal unop1 unop2) then (L.d_strln "failure reason 23"; raise IList.Fail)
+      if not (Unop.equal unop1 unop2) then (L.d_strln "failure reason 23"; raise IList.Fail)
       else Sil.UnOp (unop1, exp_partial_join e1 e2, topt1) (* should be topt1 = topt2 *)
   | Sil.BinOp(Sil.PlusPI, e1, e1'), Sil.BinOp(Sil.PlusPI, e2, e2') ->
       let e1'' = exp_partial_join e1 e2 in
@@ -1018,7 +1018,7 @@ let rec exp_partial_meet (e1: Sil.exp) (e2: Sil.exp) : Sil.exp =
         let e1'' = exp_partial_meet e1 e2 in
         Sil.Cast (t1, e1'')
   | Sil.UnOp(unop1, e1, topt1), Sil.UnOp(unop2, e2, _) ->
-      if not (Sil.unop_equal unop1 unop2) then (L.d_strln "failure reason 31"; raise IList.Fail)
+      if not (Unop.equal unop1 unop2) then (L.d_strln "failure reason 31"; raise IList.Fail)
       else Sil.UnOp (unop1, exp_partial_meet e1 e2, topt1) (* should be topt1 = topt2 *)
   | Sil.BinOp(binop1, e1, e1'), Sil.BinOp(binop2, e2, e2') ->
       if not (Sil.binop_equal binop1 binop2) then (L.d_strln "failure reason 32"; raise IList.Fail)
diff --git a/infer/src/backend/interproc.ml b/infer/src/backend/interproc.ml
index 9a5a295da..73ae9a3d2 100644
--- a/infer/src/backend/interproc.ml
+++ b/infer/src/backend/interproc.ml
@@ -400,7 +400,7 @@ let check_assignement_guard node =
       let leti = IList.filter is_letderef_instr ins in
       match pi, leti with
       | [Sil.Prune (Sil.Var(e1), _, _, _)], [Sil.Letderef(e2, e', _, _)]
-      | [Sil.Prune (Sil.UnOp(Sil.LNot, Sil.Var(e1), _), _, _, _)],
+      | [Sil.Prune (Sil.UnOp(Unop.LNot, Sil.Var(e1), _), _, _, _)],
         [Sil.Letderef(e2, e', _, _)]
         when (Ident.equal e1 e2) ->
           if verbose
@@ -430,7 +430,7 @@ let check_assignement_guard node =
   let succs_have_simple_guards () =
     let check_instr = function
       | Sil.Prune (Sil.Var _, _, _, _) -> true
-      | Sil.Prune (Sil.UnOp(Sil.LNot, Sil.Var _, _), _, _, _) -> true
+      | Sil.Prune (Sil.UnOp(Unop.LNot, Sil.Var _, _), _, _, _) -> true
       | Sil.Prune _ -> false
       | _ -> true in
     let check_guard n =
diff --git a/infer/src/backend/match.ml b/infer/src/backend/match.ml
index 8c81e94e6..0d83cab86 100644
--- a/infer/src/backend/match.ml
+++ b/infer/src/backend/match.ml
@@ -58,7 +58,7 @@ let rec exp_match e1 sub vars e2 : (Sil.subst * Ident.t list) option =
       exp_match e1' sub vars e2'
   | Sil.Cast _, _ | _, Sil.Cast _ ->
       None
-  | Sil.UnOp(o1, e1', _), Sil.UnOp(o2, e2', _) when Sil.unop_equal o1 o2 ->
+  | Sil.UnOp(o1, e1', _), Sil.UnOp(o2, e2', _) when Unop.equal o1 o2 ->
       exp_match e1' sub vars e2'
   | Sil.UnOp _, _ | _, Sil.UnOp _ ->
       None  (* Naive *)
diff --git a/infer/src/backend/modelBuiltins.ml b/infer/src/backend/modelBuiltins.ml
index 273c99705..6fa9c1901 100644
--- a/infer/src/backend/modelBuiltins.ml
+++ b/infer/src/backend/modelBuiltins.ml
@@ -180,7 +180,7 @@ let create_type tenv n_lexp typ prop =
           prop''
       | None -> prop in
   let sil_is_null = Sil.BinOp (Sil.Eq, n_lexp, Sil.exp_zero) in
-  let sil_is_nonnull = Sil.UnOp (Sil.LNot, sil_is_null, None) in
+  let sil_is_nonnull = Sil.UnOp (Unop.LNot, sil_is_null, None) in
   let null_case = Propset.to_proplist (prune ~positive:true sil_is_null prop) in
   let non_null_case = Propset.to_proplist (prune ~positive:true sil_is_nonnull prop_type) in
   if ((IList.length non_null_case) > 0) && (!Config.footprint) then
diff --git a/infer/src/backend/prop.ml b/infer/src/backend/prop.ml
index 803ec9214..5222d656f 100644
--- a/infer/src/backend/prop.ml
+++ b/infer/src/backend/prop.ml
@@ -466,41 +466,41 @@ let sym_eval abs e =
         e
     | Sil.Cast (_, e1) ->
         eval e1
-    | Sil.UnOp (Sil.LNot, e1, topt) ->
+    | Sil.UnOp (Unop.LNot, e1, topt) ->
         begin
           match eval e1 with
           | Sil.Const (Const.Cint i) when IntLit.iszero i ->
               Sil.exp_one
           | Sil.Const (Const.Cint _) ->
               Sil.exp_zero
-          | Sil.UnOp(Sil.LNot, e1', _) ->
+          | Sil.UnOp(Unop.LNot, e1', _) ->
               e1'
           | e1' ->
-              if abs then Sil.exp_get_undefined false else Sil.UnOp(Sil.LNot, e1', topt)
+              if abs then Sil.exp_get_undefined false else Sil.UnOp(Unop.LNot, e1', topt)
         end
-    | Sil.UnOp (Sil.Neg, e1, topt) ->
+    | Sil.UnOp (Unop.Neg, e1, topt) ->
         begin
           match eval e1 with
-          | Sil.UnOp (Sil.Neg, e2', _) ->
+          | Sil.UnOp (Unop.Neg, e2', _) ->
               e2'
           | Sil.Const (Const.Cint i) ->
               Sil.exp_int (IntLit.neg i)
           | Sil.Const (Const.Cfloat v) ->
               Sil.exp_float (-. v)
           | Sil.Var id ->
-              Sil.UnOp (Sil.Neg, Sil.Var id, topt)
+              Sil.UnOp (Unop.Neg, Sil.Var id, topt)
           | e1' ->
-              if abs then Sil.exp_get_undefined false else Sil.UnOp (Sil.Neg, e1', topt)
+              if abs then Sil.exp_get_undefined false else Sil.UnOp (Unop.Neg, e1', topt)
         end
-    | Sil.UnOp (Sil.BNot, e1, topt) ->
+    | Sil.UnOp (Unop.BNot, e1, topt) ->
         begin
           match eval e1 with
-          | Sil.UnOp(Sil.BNot, e2', _) ->
+          | Sil.UnOp(Unop.BNot, e2', _) ->
               e2'
           | Sil.Const (Const.Cint i) ->
               Sil.exp_int (IntLit.lognot i)
           | e1' ->
-              if abs then Sil.exp_get_undefined false else Sil.UnOp (Sil.BNot, e1', topt)
+              if abs then Sil.exp_get_undefined false else Sil.UnOp (Unop.BNot, e1', topt)
         end
     | Sil.BinOp (Sil.Le, e1, e2) ->
         begin
@@ -629,8 +629,8 @@ let sym_eval abs e =
               Sil.exp_int (n ++ m)
           | Sil.Const (Const.Cfloat v), Sil.Const (Const.Cfloat w) ->
               Sil.exp_float (v +. w)
-          | Sil.UnOp(Sil.Neg, f1, _), f2
-          | f2, Sil.UnOp(Sil.Neg, f1, _) ->
+          | Sil.UnOp(Unop.Neg, f1, _), f2
+          | f2, Sil.UnOp(Unop.Neg, f1, _) ->
               Sil.BinOp (ominus, f2, f1)
           | Sil.BinOp (Sil.PlusA, e, Sil.Const (Const.Cint n1)), Sil.Const (Const.Cint n2)
           | Sil.BinOp (Sil.PlusPI, e, Sil.Const (Const.Cint n1)), Sil.Const (Const.Cint n2)
@@ -666,14 +666,14 @@ let sym_eval abs e =
         else begin
           match e1', e2' with
           | Sil.Const c, _ when iszero_int_float c ->
-              eval (Sil.UnOp(Sil.Neg, e2', None))
+              eval (Sil.UnOp(Unop.Neg, e2', None))
           | _, Sil.Const c when iszero_int_float c ->
               e1'
           | Sil.Const (Const.Cint n), Sil.Const (Const.Cint m) ->
               Sil.exp_int (n -- m)
           | Sil.Const (Const.Cfloat v), Sil.Const (Const.Cfloat w) ->
               Sil.exp_float (v -. w)
-          | _, Sil.UnOp (Sil.Neg, f2, _) ->
+          | _, Sil.UnOp (Unop.Neg, f2, _) ->
               eval (e1 +++ f2)
           | _ , Sil.Const(Const.Cint n) ->
               eval (e1' +++ (Sil.exp_int (IntLit.neg n)))
@@ -697,13 +697,13 @@ let sym_eval abs e =
           | Sil.Const c, _ when isone_int_float c ->
               e2'
           | Sil.Const c, _ when isminusone_int_float c ->
-              eval (Sil.UnOp (Sil.Neg, e2', None))
+              eval (Sil.UnOp (Unop.Neg, e2', None))
           | _, Sil.Const c when iszero_int_float c ->
               Sil.exp_zero
           | _, Sil.Const c when isone_int_float c ->
               e1'
           | _, Sil.Const c when isminusone_int_float c ->
-              eval (Sil.UnOp (Sil.Neg, e1', None))
+              eval (Sil.UnOp (Unop.Neg, e1', None))
           | Sil.Const (Const.Cint n), Sil.Const (Const.Cint m) ->
               Sil.exp_int (IntLit.mul n m)
           | Sil.Const (Const.Cfloat v), Sil.Const (Const.Cfloat w) ->
@@ -891,7 +891,7 @@ let mk_inequality e =
            let new_offset = Sil.exp_int (n' -- n -- IntLit.one) in
            let new_e = Sil.BinOp (Sil.Lt, new_offset, base') in
            Sil.Aeq (new_e, Sil.exp_one)
-       | Sil.UnOp(Sil.Neg, new_base, _) ->
+       | Sil.UnOp(Unop.Neg, new_base, _) ->
            (* In this case, base = -new_base. Construct -n-1 < new_base. *)
            let new_offset = Sil.exp_int (IntLit.zero -- n -- IntLit.one) in
            let new_e = Sil.BinOp (Sil.Lt, new_offset, new_base) in
@@ -917,7 +917,7 @@ let mk_inequality e =
            let new_offset = Sil.exp_int (n' -- n -- IntLit.one) in
            let new_e = Sil.BinOp (Sil.Le, base', new_offset) in
            Sil.Aeq (new_e, Sil.exp_one)
-       | Sil.UnOp(Sil.Neg, new_base, _) ->
+       | Sil.UnOp(Unop.Neg, new_base, _) ->
            (* In this case, base = -new_base. Construct new_base <= -n-1 *)
            let new_offset = Sil.exp_int (IntLit.zero -- n -- IntLit.one) in
            let new_e = Sil.BinOp (Sil.Le, new_base, new_offset) in
@@ -942,7 +942,7 @@ let inequality_normalize a =
         let pos1, neg1, n1 = exp_to_posnegoff e1 in
         let pos2, neg2, n2 = exp_to_posnegoff e2 in
         (pos1@neg2, neg1@pos2, n1 -- n2)
-    | Sil.UnOp(Sil.Neg, e1, _) ->
+    | Sil.UnOp(Unop.Neg, e1, _) ->
         let pos1, neg1, n1 = exp_to_posnegoff e1 in
         (neg1, pos1, IntLit.zero -- n1)
     | _ -> [e],[], IntLit.zero in
@@ -1015,8 +1015,8 @@ let atom_normalize sub a0 =
     | _ -> eq in
   let handle_unary_negation e1 e2 =
     match e1, e2 with
-    | Sil.UnOp (Sil.LNot, e1', _), Sil.Const (Const.Cint i)
-    | Sil.Const (Const.Cint i), Sil.UnOp (Sil.LNot, e1', _) when IntLit.iszero i ->
+    | Sil.UnOp (Unop.LNot, e1', _), Sil.Const (Const.Cint i)
+    | Sil.Const (Const.Cint i), Sil.UnOp (Unop.LNot, e1', _) when IntLit.iszero i ->
         (e1', Sil.exp_zero, true)
     | _ -> (e1, e2, false) in
   let handle_boolean_operation from_equality e1 e2 =
@@ -1974,7 +1974,7 @@ let find_arithmetic_problem proc_node_session prop exp =
         false in
   let rec walk = function
     | Sil.Var _ -> ()
-    | Sil.UnOp (Sil.Neg, e, Some (
+    | Sil.UnOp (Unop.Neg, e, Some (
         (Typ.Tint
            (Typ.IUChar | Typ.IUInt | Typ.IUShort | Typ.IULong | Typ.IULongLong) as typ))) ->
         uminus_unsigned := (e, typ) :: !uminus_unsigned
@@ -2779,8 +2779,8 @@ let trans_land_lor op ((idl1, stml1), e1) ((idl2, stml2), e2) loc =
       let id = Ident.create_fresh Ident.knormal in
       let prune_instr1, prune_res1, prune_instr2, prune_res2 =
         let cond1, cond2, res = match op with
-          | Sil.LAnd -> e1, Sil.UnOp(Sil.LNot, e1, None), IntLit.zero
-          | Sil.LOr -> Sil.UnOp(Sil.LNot, e1, None), e1, IntLit.one
+          | Sil.LAnd -> e1, Sil.UnOp(Unop.LNot, e1, None), IntLit.zero
+          | Sil.LOr -> Sil.UnOp(Unop.LNot, e1, None), e1, IntLit.one
           | _ -> assert false in
         let cond_res1 = Sil.BinOp(Sil.Eq, Sil.Var id, e2) in
         let cond_res2 = Sil.BinOp(Sil.Eq, Sil.Var id, Sil.exp_int res) in
@@ -2836,7 +2836,7 @@ let trans_if_then_else ((idl1, stml1), e1) ((idl2, stml2), e2) ((idl3, stml3), e
   | Sil.Const (Const.Cint i) when IntLit.iszero i -> (idl1@idl3, stml1@stml3), e3
   | Sil.Const (Const.Cint _) -> (idl1@idl2, stml1@stml2), e2
   | _ ->
-      let e1not = Sil.UnOp(Sil.LNot, e1, None) in
+      let e1not = Sil.UnOp(Unop.LNot, e1, None) in
       let id = Ident.create_fresh Ident.knormal in
       let mk_prune_res e =
         let mk_prune cond = Sil.Prune (cond, loc, true, Sil.Ik_land_lor)
diff --git a/infer/src/backend/symExec.ml b/infer/src/backend/symExec.ml
index fe0beec6a..59bbd49bb 100644
--- a/infer/src/backend/symExec.ml
+++ b/infer/src/backend/symExec.ml
@@ -324,7 +324,7 @@ let rec prune ~positive condition prop =
       assert false
   | Sil.Cast (_, condition') ->
       prune ~positive condition' prop
-  | Sil.UnOp (Sil.LNot, condition', _) ->
+  | Sil.UnOp (Unop.LNot, condition', _) ->
       prune ~positive:(not positive) condition' prop
   | Sil.UnOp _ ->
       assert false
@@ -445,7 +445,7 @@ let check_already_dereferenced pname cond prop =
   let rec is_check_zero = function
     | Sil.Var id ->
         Some id
-    | Sil.UnOp(Sil.LNot, e, _) ->
+    | Sil.UnOp(Unop.LNot, e, _) ->
         is_check_zero e
     | Sil.BinOp ((Sil.Eq | Sil.Ne), Sil.Const Const.Cint i, Sil.Var id)
     | Sil.BinOp ((Sil.Eq | Sil.Ne), Sil.Var id, Sil.Const Const.Cint i) when IntLit.iszero i ->
diff --git a/infer/src/checkers/annotationReachability.ml b/infer/src/checkers/annotationReachability.ml
index 0f205fae0..dffd6a30c 100644
--- a/infer/src/checkers/annotationReachability.ml
+++ b/infer/src/checkers/annotationReachability.ml
@@ -291,7 +291,7 @@ module TransferFunctions (CFG : ProcCfg.S) = struct
     | Sil.BinOp (Sil.Eq, lhs, rhs)
       when is_tracking_exp astate lhs ->
         Sil.exp_equal rhs Sil.exp_one
-    | Sil.UnOp (Sil.LNot, Sil.BinOp (Sil.Eq, lhs, rhs), _)
+    | Sil.UnOp (Unop.LNot, Sil.BinOp (Sil.Eq, lhs, rhs), _)
       when is_tracking_exp astate lhs ->
         Sil.exp_equal rhs Sil.exp_zero
     | _ ->
diff --git a/infer/src/checkers/checkTraceCallSequence.ml b/infer/src/checkers/checkTraceCallSequence.ml
index f1f51dbbe..bd8c1da29 100644
--- a/infer/src/checkers/checkTraceCallSequence.ml
+++ b/infer/src/checkers/checkTraceCallSequence.ml
@@ -244,9 +244,9 @@ module BooleanVars = struct
     (** Normalize a boolean condition. *)
     let normalize_condition cond_e =
       match cond_e with
-      | Sil.UnOp (Sil.LNot, Sil.BinOp (Sil.Eq, e1, e2), _) ->
+      | Sil.UnOp (Unop.LNot, Sil.BinOp (Sil.Eq, e1, e2), _) ->
           Sil.BinOp (Sil.Ne, e1, e2)
-      | Sil.UnOp (Sil.LNot, Sil.BinOp (Sil.Ne, e1, e2), _) ->
+      | Sil.UnOp (Unop.LNot, Sil.BinOp (Sil.Ne, e1, e2), _) ->
           Sil.BinOp (Sil.Eq, e1, e2)
       | _ -> cond_e in
 
diff --git a/infer/src/checkers/codeQuery.ml b/infer/src/checkers/codeQuery.ml
index 0d0a4dc37..5e866a723 100644
--- a/infer/src/checkers/codeQuery.ml
+++ b/infer/src/checkers/codeQuery.ml
@@ -127,9 +127,9 @@ module Match = struct
         let e1 = Idenv.expand_expr idenv _e1 in
         let e2 = Idenv.expand_expr idenv _e2 in
         binop_match bop op && exp_match env ae1 (Vval e1) && exp_match env ae2 (Vval e2)
-    | Sil.UnOp (Sil.LNot, (Sil.BinOp (Sil.Eq, e1, e2)), _) ->
+    | Sil.UnOp (Unop.LNot, (Sil.BinOp (Sil.Eq, e1, e2)), _) ->
         cond_match env idenv (Sil.BinOp (Sil.Ne, e1, e2)) (ae1, op, ae2)
-    | Sil.UnOp (Sil.LNot, (Sil.BinOp (Sil.Ne, e1, e2)), _) ->
+    | Sil.UnOp (Unop.LNot, (Sil.BinOp (Sil.Ne, e1, e2)), _) ->
         cond_match env idenv (Sil.BinOp (Sil.Eq, e1, e2)) (ae1, op, ae2)
     | _ -> false
 
diff --git a/infer/src/clang/cArithmetic_trans.ml b/infer/src/clang/cArithmetic_trans.ml
index 3ed6cf7a0..25614dfbd 100644
--- a/infer/src/clang/cArithmetic_trans.ml
+++ b/infer/src/clang/cArithmetic_trans.ml
@@ -169,10 +169,10 @@ let unary_operation_instruction uoi e typ loc =
         else
           e_minus_1 in
       (exp, instr1::[Sil.Set (e, typ, e_minus_1, loc)])
-  | `Not -> (un_exp (Sil.BNot), [])
-  | `Minus -> (un_exp (Sil.Neg), [])
+  | `Not -> (un_exp (Unop.BNot), [])
+  | `Minus -> (un_exp (Unop.Neg), [])
   | `Plus -> (e, [])
-  | `LNot -> (un_exp (Sil.LNot), [])
+  | `LNot -> (un_exp (Unop.LNot), [])
   | `Deref ->
       (* Actual dereferencing is handled by implicit cast from rvalue to lvalue *)
       (e, [])
diff --git a/infer/src/eradicate/typeCheck.ml b/infer/src/eradicate/typeCheck.ml
index 6853b9b1d..fa4cad14d 100644
--- a/infer/src/eradicate/typeCheck.ml
+++ b/infer/src/eradicate/typeCheck.ml
@@ -123,7 +123,7 @@ module ComplexExpressions = struct
       | Sil.Dpvaraddr _ (* front-end variable -- this should not happen) *) ->
           case_not_handled ()
       | Sil.Dunop (op, de) ->
-          Sil.str_unop op ^ dexp_to_string de
+          Unop.str op ^ dexp_to_string de
       | Sil.Dsizeof _ ->
           case_not_handled ()
       | Sil.Dunknown ->
@@ -1023,9 +1023,9 @@ let typecheck_instr
                   else typestate2
             end
 
-        | Sil.UnOp (Sil.LNot, (Sil.BinOp (Sil.Eq, e1, e2)), _) ->
+        | Sil.UnOp (Unop.LNot, (Sil.BinOp (Sil.Eq, e1, e2)), _) ->
             check_condition node' (Sil.BinOp (Sil.Ne, e1, e2))
-        | Sil.UnOp (Sil.LNot, (Sil.BinOp (Sil.Ne, e1, e2)), _) ->
+        | Sil.UnOp (Unop.LNot, (Sil.BinOp (Sil.Ne, e1, e2)), _) ->
             check_condition node' (Sil.BinOp (Sil.Eq, e1, e2))
         | _ -> typestate in
 
@@ -1046,9 +1046,9 @@ let typecheck_instr
 
       (** Normalize the condition by resolving temp variables. *)
       let rec normalize_cond _node _cond = match _cond with
-        | Sil.UnOp (Sil.LNot, c, top) ->
+        | Sil.UnOp (Unop.LNot, c, top) ->
             let node', c' = normalize_cond _node c in
-            node', Sil.UnOp (Sil.LNot, c', top)
+            node', Sil.UnOp (Unop.LNot, c', top)
         | Sil.BinOp (bop, c1, c2) ->
             let node', c1' = normalize_cond _node c1 in
             let node'', c2' = normalize_cond node' c2 in
diff --git a/infer/src/java/jTrans.ml b/infer/src/java/jTrans.ml
index 8da6bf844..518f09fb5 100644
--- a/infer/src/java/jTrans.ml
+++ b/infer/src/java/jTrans.ml
@@ -438,7 +438,7 @@ let rec expression context pc expr =
       let (instrs, sil_ex, _) = expression context pc ex in
       begin
         match unop with
-        | JBir.Neg _ -> (instrs, Sil.UnOp (Sil.Neg, sil_ex, Some type_of_expr), type_of_expr)
+        | JBir.Neg _ -> (instrs, Sil.UnOp (Unop.Neg, sil_ex, Some type_of_expr), type_of_expr)
         | JBir.ArrayLength ->
             let array_typ_no_ptr =
               match type_of_ex with
@@ -874,7 +874,7 @@ let rec instruction context pc instr : translation =
         and (instrs2, sil_ex2, _) = expression context pc e2 in
         let sil_op = get_test_operator op in
         let sil_test_false = Sil.BinOp (sil_op, sil_ex1, sil_ex2) in
-        let sil_test_true = Sil.UnOp(Sil.LNot, sil_test_false, None) in
+        let sil_test_true = Sil.UnOp(Unop.LNot, sil_test_false, None) in
         let sil_instrs_true = Sil.Prune (sil_test_true, loc, true, Sil.Ik_if) in
         let sil_instrs_false = Sil.Prune (sil_test_false, loc, false, Sil.Ik_if) in
         let node_kind_true = Cfg.Node.Prune_node (true, Sil.Ik_if, "method_body") in
diff --git a/infer/src/java/jTransExn.ml b/infer/src/java/jTransExn.ml
index 3b64ace1f..f3302ffc1 100644
--- a/infer/src/java/jTransExn.ml
+++ b/infer/src/java/jTransExn.ml
@@ -73,7 +73,8 @@ let translate_exceptions context exit_nodes get_body_nodes handler_table =
           Sil.Call ([id_instanceof], instanceof_builtin, args, loc, Sil.cf_default) in
         let if_kind = Sil.Ik_switch in
         let instr_prune_true = Sil.Prune (Sil.Var id_instanceof, loc, true, if_kind) in
-        let instr_prune_false = Sil.Prune (Sil.UnOp(Sil.LNot, Sil.Var id_instanceof, None), loc, false, if_kind) in
+        let instr_prune_false =
+          Sil.Prune (Sil.UnOp(Unop.LNot, Sil.Var id_instanceof, None), loc, false, if_kind) in
         let instr_set_catch_var =
           let catch_var = JContext.set_pvar context handler.JBir.e_catch_var ret_type in
           Sil.Set (Sil.Lvar catch_var, ret_type, Sil.Var id_exn_val, loc) in
diff --git a/infer/src/unit/analyzerTester.ml b/infer/src/unit/analyzerTester.ml
index 0121548ad..9143862b0 100644
--- a/infer/src/unit/analyzerTester.ml
+++ b/infer/src/unit/analyzerTester.ml
@@ -165,7 +165,7 @@ module Make
         create_node (Cfg.Node.Prune_node (true_branch, if_kind, "")) [prune_instr] in
       let true_prune_node = mk_prune_node cond_exp if_kind true in
       let false_prune_node =
-        let negated_cond_exp = Sil.UnOp (Sil.LNot, cond_exp, None) in
+        let negated_cond_exp = Sil.UnOp (Unop.LNot, cond_exp, None) in
         mk_prune_node negated_cond_exp if_kind false in
       true_prune_node, false_prune_node in