diff --git a/infer/src/Makefile.in b/infer/src/Makefile.in
index f5e439ce7..e70e48603 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,@33 \
                      -cflags -w,@34 \
                      -cflags -w,@35 \
                      -cflags -w,@37 \
diff --git a/infer/src/backend/inferanalyze.ml b/infer/src/backend/inferanalyze.ml
index 3f69b5a32..5969eed79 100644
--- a/infer/src/backend/inferanalyze.ml
+++ b/infer/src/backend/inferanalyze.ml
@@ -12,7 +12,6 @@
 
 module L = Logging
 module F = Format
-open Yojson.Basic.Util
 
 (* This module, unused by default, generates random c files with procedure calls *)
 module Codegen = struct
diff --git a/infer/src/backend/procname.ml b/infer/src/backend/procname.ml
index f996b9dde..06e7092cc 100644
--- a/infer/src/backend/procname.ml
+++ b/infer/src/backend/procname.ml
@@ -12,7 +12,6 @@
 
 module L = Logging
 module F = Format
-open Str
 
 type java_type = string option * string (* e.g. ("", "int") for primitive types or ("java.io", "PrintWriter") for objects *)
 
diff --git a/infer/src/backend/prover.mli b/infer/src/backend/prover.mli
index 884abd76d..4eb1733b4 100644
--- a/infer/src/backend/prover.mli
+++ b/infer/src/backend/prover.mli
@@ -10,7 +10,6 @@
 
 (** Functions for Theorem Proving *)
 
-open Ident
 open Sil
 
 (** {2 Ordinary Theorem Proving} *)
diff --git a/infer/src/clang/cContext.ml b/infer/src/clang/cContext.ml
index 94deaf9ae..8cc67c5ee 100644
--- a/infer/src/clang/cContext.ml
+++ b/infer/src/clang/cContext.ml
@@ -10,7 +10,6 @@
 (** Contains current class and current method to be translated as well as local variables, *)
 (** and the cg, cfg, and tenv corresponding to the current file. *)
 
-open CFrontend_utils
 module L = Logging
 
 type curr_class =
diff --git a/infer/src/clang/cEnum_decl.mli b/infer/src/clang/cEnum_decl.mli
index 9c07ab849..56941919b 100644
--- a/infer/src/clang/cEnum_decl.mli
+++ b/infer/src/clang/cEnum_decl.mli
@@ -9,6 +9,5 @@
 
 (** Translate an enumeration declaration by adding it to the tenv and *)
 (** translating the code and adding it to a fake procdesc *)
-open CFrontend_utils
 
 val enum_decl : Clang_ast_t.decl -> Sil.typ
diff --git a/infer/src/clang/cTrans.ml b/infer/src/clang/cTrans.ml
index 85966ff02..f040fc4f7 100644
--- a/infer/src/clang/cTrans.ml
+++ b/infer/src/clang/cTrans.ml
@@ -560,7 +560,6 @@ struct
     { empty_res_trans with root_nodes = [root_node']; leaf_nodes = trans_state.succ_nodes }
 
   and decl_ref_trans trans_state pre_trans_result stmt_info decl_ref =
-    let open CContext in
     Printing.log_out "  priority node free = '%s'\n@."
       (string_of_bool (PriorityNode.is_priority_free trans_state));
     let decl_kind = decl_ref.Clang_ast_t.dr_kind in
@@ -580,7 +579,6 @@ struct
         print_error decl_kind; assert false
 
   and declRefExpr_trans trans_state stmt_info expr_info decl_ref_expr_info e =
-    let open CContext in
     Printing.log_out "  priority node free = '%s'\n@."
       (string_of_bool (PriorityNode.is_priority_free trans_state));
     let decl_ref = match decl_ref_expr_info.Clang_ast_t.drti_decl_ref with
@@ -1706,7 +1704,6 @@ struct
   (* the stmt_list will be [x.f = a; x; a; CallToSetter] Among all element of the list we only need*)
   (* to translate the CallToSetter which is how x.f = a is actually implemented by the runtime.*)
   and pseudoObjectExpr_trans trans_state stmt_info stmt_list =
-    let open Clang_ast_t in
     Printing.log_out "  priority node free = '%s'\n@."
       (string_of_bool (PriorityNode.is_priority_free trans_state));
     let rec do_semantic_elements el =
diff --git a/infer/src/clang/cTypes_decl.ml b/infer/src/clang/cTypes_decl.ml
index e122ca1a1..750fe1987 100644
--- a/infer/src/clang/cTypes_decl.ml
+++ b/infer/src/clang/cTypes_decl.ml
@@ -43,7 +43,6 @@ let add_predefined_objc_types tenv =
 (* they should be added here too!! *)
 let add_predefined_basic_types tenv =
   let open Ast_expressions in
-  let open Clang_ast_t in
   let add_basic_type tp basic_type_kind =
     let sil_type = CType_to_sil_type.sil_type_of_builtin_type_kind basic_type_kind in
     Ast_utils.update_sil_types_map tp sil_type in
diff --git a/infer/src/java/jClasspath.ml b/infer/src/java/jClasspath.ml
index 221bdf195..894352507 100644
--- a/infer/src/java/jClasspath.ml
+++ b/infer/src/java/jClasspath.ml
@@ -9,7 +9,6 @@
  *)
 
 open Javalib_pack
-open Sawja_pack
 
 module L = Logging
 
diff --git a/infer/src/java/jClasspath.mli b/infer/src/java/jClasspath.mli
index 2fb48bf9d..09ac90638 100644
--- a/infer/src/java/jClasspath.mli
+++ b/infer/src/java/jClasspath.mli
@@ -9,7 +9,6 @@
  *)
 
 open Javalib_pack
-open Sawja_pack
 
 (** Jar file containing the models *)
 val models_jar : string ref
diff --git a/infer/src/java/jFrontend.mli b/infer/src/java/jFrontend.mli
index 72c329892..6896c43e8 100644
--- a/infer/src/java/jFrontend.mli
+++ b/infer/src/java/jFrontend.mli
@@ -9,7 +9,6 @@
  *)
 
 open Javalib_pack
-open Sawja_pack
 
 (** [path_of_cached_classname cn] returns the path of a cached classname *)
 val path_of_cached_classname : JBasics.class_name -> string
diff --git a/infer/src/java/jTransExn.mli b/infer/src/java/jTransExn.mli
index 7062d0ee7..e5832af79 100644
--- a/infer/src/java/jTransExn.mli
+++ b/infer/src/java/jTransExn.mli
@@ -8,7 +8,6 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  *)
 
-open Javalib_pack
 open Sawja_pack
 
 
diff --git a/infer/src/java/jUtils.mli b/infer/src/java/jUtils.mli
index efb29a1de..b2cdb0e31 100644
--- a/infer/src/java/jUtils.mli
+++ b/infer/src/java/jUtils.mli
@@ -8,8 +8,5 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  *)
 
-open Javalib_pack
-
-
 (** TODO: replace by a Infer-wide debug mode printing *)
 val log : ('a, Format.formatter, unit) format -> 'a
diff --git a/infer/src/llvm/lLexer.mll b/infer/src/llvm/lLexer.mll
index 56373c170..4187d5bd3 100644
--- a/infer/src/llvm/lLexer.mll
+++ b/infer/src/llvm/lLexer.mll
@@ -8,7 +8,6 @@
  *)
 
 {
-  open Lexing
   open LParser
 
   exception LexingError of string
diff --git a/infer/src/llvm/lTrans.ml b/infer/src/llvm/lTrans.ml
index da28ab529..9c929bd93 100644
--- a/infer/src/llvm/lTrans.ml
+++ b/infer/src/llvm/lTrans.ml
@@ -125,7 +125,6 @@ let trans_function_def (cfg : Cfg.cfg) (cg: Cg.t) (metadata : LAst.metadata_map)
         | None -> Sil.Tvoid
         | Some ret_tp -> trans_typ ret_tp in
       let (proc_attrs : ProcAttributes.t) =
-        let open Sil in
         { (ProcAttributes.default proc_name Config.C_CPP) with
           ProcAttributes.formals =
             IList.map (fun (tp, name) -> (Mangled.from_string name, trans_typ tp)) params;
diff --git a/infer/src/opensource/taint.ml b/infer/src/opensource/taint.ml
index 2f85b58ac..4d6c2dac9 100644
--- a/infer/src/opensource/taint.ml
+++ b/infer/src/opensource/taint.ml
@@ -7,8 +7,6 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  *)
 
-module L = Logging
-
 (** returns true if [callee_pname] returns a tainted value *)
 let returns_secret callee_pname = false