diff --git a/infer/src/Makefile.in b/infer/src/Makefile.in
index 4e41b9b5c..371f4ea0e 100644
--- a/infer/src/Makefile.in
+++ b/infer/src/Makefile.in
@@ -91,6 +91,7 @@ OCAMLBUILD_OPTIONS = \
                      -cflags -w,@19 \
                      -cflags -w,@20 \
                      -cflags -w,@26 \
+                     -cflags -w,@34 \
                      -cflags -w,@35 \
                      -cflags -w,@37 \
                      -cflags -w,@38 \
diff --git a/infer/src/backend/DB.ml b/infer/src/backend/DB.ml
index 033372883..2d9e25d9a 100644
--- a/infer/src/backend/DB.ml
+++ b/infer/src/backend/DB.ml
@@ -59,9 +59,6 @@ let rel_source_file_from_abs_path root fname =
     (* The project root is not a prefix of the file name *)
     abs_source_file_from_path fname
 
-type encoding_type =
-  [ `Enc_base | `Enc_path_with_underscores | `Enc_crc ]
-
 let curr_encoding = `Enc_crc
 
 let source_file_to_string fname =
diff --git a/infer/src/backend/autounit.ml b/infer/src/backend/autounit.ml
index f3ea69b6f..fcc8ac7e9 100644
--- a/infer/src/backend/autounit.ml
+++ b/infer/src/backend/autounit.ml
@@ -53,7 +53,7 @@ end = struct
     IdMap.iter do_id ev
 
   (** create a new evaluation *)
-  let new_eval vars =
+  let new_eval vars : eval =
     let ev = ref IdMap.empty in
     let add_var id =
       ev := IdMap.add id (new_range ()) !ev in
diff --git a/infer/src/backend/dom.ml b/infer/src/backend/dom.ml
index 874c4c577..795c19515 100644
--- a/infer/src/backend/dom.ml
+++ b/infer/src/backend/dom.ml
@@ -459,7 +459,7 @@ module FreshVarExp : sig
 
   val init : unit -> unit
   val get_fresh_exp : Sil.exp -> Sil.exp -> Sil.exp
-  val get_induced_pi : unit -> Sil.atom list
+  val get_induced_pi : unit -> pi
   val lookup : side -> Sil.exp -> (Sil.exp * Sil.exp) option
   val final : unit -> unit
 
@@ -566,7 +566,8 @@ module Rename : sig
 end = struct
 
   type t = (Sil.exp * Sil.exp * Sil.exp) list
-  let tbl = ref []
+
+  let tbl : t ref = ref []
   let empty = []
 
   let init () = tbl := []
@@ -1578,7 +1579,7 @@ let widening_bottom = Sil.Int.of_int64 Int64.min_int ++ Sil.Int.of_int 1000 (* n
 (** {2 Join and Meet for Pi} *)
 let pi_partial_join mode
     (ep1: Prop.exposed Prop.t) (ep2: Prop.exposed Prop.t)
-    (pi1: Sil.atom list) (pi2: Sil.atom list) : Sil.atom list
+    (pi1: pi) (pi2: pi) : pi
   =
   let exp_is_const = function
     (* | Sil.Var id -> is_normal id *)
diff --git a/infer/src/backend/prop.ml b/infer/src/backend/prop.ml
index b9b682b26..97248828b 100644
--- a/infer/src/backend/prop.ml
+++ b/infer/src/backend/prop.ml
@@ -48,9 +48,6 @@ type 'a t =
 
 exception Cannot_star of ml_loc
 
-(** Pure proposition. *)
-type pure_prop = Sil.subst * Sil.atom list
-
 (** {2 Basic Functions for Propositions} *)
 
 (** {1 Functions for Comparison} *)
diff --git a/infer/src/backend/sil.ml b/infer/src/backend/sil.ml
index 22899b252..b5ac55401 100644
--- a/infer/src/backend/sil.ml
+++ b/infer/src/backend/sil.ml
@@ -234,7 +234,7 @@ module Subtype = struct
 
   type subtMap = bool SubtypesMap.t
 
-  let subtMap = ref SubtypesMap.empty
+  let subtMap : subtMap ref = ref SubtypesMap.empty
 
   let check_subtype f c1 c2 =
     try
diff --git a/infer/src/backend/specs.ml b/infer/src/backend/specs.ml
index 876c9c413..9e591fa8f 100644
--- a/infer/src/backend/specs.ml
+++ b/infer/src/backend/specs.ml
@@ -209,8 +209,6 @@ end = struct
     normalize spec'
 end
 
-type norm_spec = NormSpec.t
-
 (** Convert spec into normal form w.r.t. variable renaming *)
 let spec_normalize =
   NormSpec.normalize
diff --git a/infer/src/checkers/constantPropagation.ml b/infer/src/checkers/constantPropagation.ml
index 277318d01..60e9bfde8 100644
--- a/infer/src/checkers/constantPropagation.ml
+++ b/infer/src/checkers/constantPropagation.ml
@@ -11,8 +11,6 @@ open Utils
 
 module L = Logging
 
-type t
-
 
 let string_widening_limit = 1000
 let verbose = false