diff --git a/infer/src/deadcode/dune.in b/infer/src/deadcode/dune.in
index 4ce20eba5..8976cfedb 100644
--- a/infer/src/deadcode/dune.in
+++ b/infer/src/deadcode/dune.in
@@ -16,7 +16,7 @@ Format.sprintf
  (ocamlopt_flags (%s))
  (libraries %s)
  (modules All_infer_in_one_file)
- (preprocess (pps ppx_compare ppx_fields_conv ppx_hash ppx_sexp_conv ppx_variants_conv -no-check))
+ (preprocess (pps ppx_compare ppx_fields_conv ppx_hash ppx_let ppx_sexp_conv ppx_variants_conv -no-check))
 )
 |}
   (String.concat " " common_cflags)
diff --git a/infer/src/dune.common.in b/infer/src/dune.common.in
index 7aeefb9a8..67c05c37d 100644
--- a/infer/src/dune.common.in
+++ b/infer/src/dune.common.in
@@ -68,6 +68,7 @@ let common_libraries =
   @ [ "ANSITerminal"
     ; "apron"
     ; "apron.octMPQ"
+    ; "async"
     ; "atdgen"
     ; "base"
     ; "base64"
diff --git a/infer/src/dune.in b/infer/src/dune.in
index 7038c0e26..af99a5c4d 100644
--- a/infer/src/dune.in
+++ b/infer/src/dune.in
@@ -65,7 +65,7 @@ let stanzas =
  (ocamlopt_flags (%s))
  (libraries %s)
  (modules :standard \ %s infertop)
- (preprocess (pps ppx_compare ppx_fields_conv ppx_hash ppx_sexp_conv ppx_variants_conv -no-check))
+ (preprocess (pps ppx_compare ppx_fields_conv ppx_hash ppx_let ppx_sexp_conv ppx_variants_conv -no-check))
 )
 
 (documentation
@@ -85,7 +85,7 @@ let stanzas =
  (ocamlopt_flags (%s))
  (libraries InferModules)
  (modules %s)
- (preprocess (pps ppx_compare ppx_fields_conv ppx_hash ppx_sexp_conv ppx_variants_conv -no-check))
+ (preprocess (pps ppx_compare ppx_fields_conv ppx_hash ppx_let ppx_sexp_conv ppx_variants_conv -no-check))
 )
 |}
         (String.concat " " infer_binaries)
@@ -99,7 +99,7 @@ let stanzas =
  (flags (%s))
  (libraries utop InferModules)
  (modules Infertop)
- (preprocess (pps ppx_compare ppx_fields_conv ppx_hash ppx_sexp_conv ppx_variants_conv -no-check))
+ (preprocess (pps ppx_compare ppx_fields_conv ppx_hash ppx_let ppx_sexp_conv ppx_variants_conv -no-check))
  (link_flags (-linkall -warn-error -31))
 )
 |}
diff --git a/opam b/opam
index 8aff00630..15e00e199 100644
--- a/opam
+++ b/opam
@@ -22,6 +22,7 @@ install: [
 depends: [
   "ANSITerminal" {>="0.7"}
   "apron"
+  "async" {>="v0.12.0" & < "v0.13"}
   "atdgen" {>="2.0.0"}
   "base64" {>="3.0.0"}
   "cmdliner" {>="1.0.0"}
@@ -43,6 +44,7 @@ depends: [
   "parmap" {>="1.0-rc8"}
   "ppx_deriving" {>="4.1"}
   "ppx_fields_conv" {>="v0.12.0" & < "v0.13"}
+  "ppx_let" {>="v0.12.0" & < "v0.13"}
   "sawja" {>="1.5.7"}
   "sqlite3"
   "utop" {with-test}
diff --git a/opam.locked b/opam.locked
index e73e88e1f..939b43cb8 100644
--- a/opam.locked
+++ b/opam.locked
@@ -22,6 +22,11 @@ install: [
 depends: [
   "ANSITerminal" {= "0.8.1"}
   "apron" {= "20160125"}
+  "async" {= "v0.12.0"}
+  "async_extra" {= "v0.12.0"}
+  "async_kernel" {= "v0.12.0"}
+  "async_rpc_kernel" {= "v0.12.0"}
+  "async_unix" {= "v0.12.0"}
   "atd" {= "2.0.0"}
   "atdgen" {= "2.0.0"}
   "atdgen-runtime" {= "2.0.0"}
@@ -109,6 +114,7 @@ depends: [
   "ppx_variants_conv" {= "v0.12.0"}
   "ppxfind" {= "1.3"}
   "ppxlib" {= "0.8.0"}
+  "protocol_version_header" {= "v0.12.0"}
   "re" {= "1.9.0"}
   "result" {= "1.4"}
   "sawja" {= "1.5.7"}
@@ -119,6 +125,7 @@ depends: [
   "splittable_random" {= "v0.12.0"}
   "sqlite3" {= "4.4.1"}
   "stdio" {= "v0.12.0"}
+  "textutils" {= "v0.12.0"}
   "time_now" {= "v0.12.0"}
   "topkg" {= "1.0.0"}
   "typerep" {= "v0.12.0"}