diff --git a/packages/ambient-context-lwt/ambient-context-lwt.0.1.0/opam b/packages/ambient-context-lwt/ambient-context-lwt.0.1.0/opam
index 75a9d38f7d0..d7b0919c3d5 100644
--- a/packages/ambient-context-lwt/ambient-context-lwt.0.1.0/opam
+++ b/packages/ambient-context-lwt/ambient-context-lwt.0.1.0/opam
@@ -11,7 +11,7 @@ depends: [
   "ocaml" {>= "4.08"}
   "ambient-context" {= version}
   "lwt"
-  "alcotest" {with-test}
+  "alcotest" {with-test & >= "1.2.0"}
   "alcotest-lwt" {with-test}
   "bisect_ppx" {with-test}
   "odoc" {with-doc}
diff --git a/packages/dbf/dbf.0.1.1/opam b/packages/dbf/dbf.0.1.1/opam
index 22f71223b56..7e66a0ac881 100644
--- a/packages/dbf/dbf.0.1.1/opam
+++ b/packages/dbf/dbf.0.1.1/opam
@@ -6,7 +6,7 @@ homepage: "https://github.com/pveber/dbf"
 bug-reports: "https://github.com/pveber/dbf/issues"
 dev-repo: "git+https://github.com/pveber/dbf.git"
 depends: [
-  "core_kernel"  {>= "v0.14.0"}
+  "core_kernel" {>= "v0.14.0" & < "v0.17.0"}
   "cstruct-unix" {>= "4.0.0"}
   "ppx_cstruct" {>= "4.0.0"}
   "rresult" {>= "0.6.0"}
diff --git a/packages/distributed/distributed.0.2.0/opam b/packages/distributed/distributed.0.2.0/opam
index be8726d92a2..48348508acf 100644
--- a/packages/distributed/distributed.0.2.0/opam
+++ b/packages/distributed/distributed.0.2.0/opam
@@ -17,7 +17,7 @@ build: [
 install: ["ocaml" "setup.ml" "-install"]
 remove: ["ocamlfind" "remove" "distributed"]
 depends: [
-  "ocaml" {>= "4.02.3"}
+  "ocaml" {>= "4.02.3" & < "5.0"}
   "base-threads"
   "base-unix"
   "batteries"
diff --git a/packages/distributed/distributed.0.3.0/opam b/packages/distributed/distributed.0.3.0/opam
index 693ddf3dca0..0b71dacb886 100644
--- a/packages/distributed/distributed.0.3.0/opam
+++ b/packages/distributed/distributed.0.3.0/opam
@@ -17,7 +17,7 @@ build: [
 install: ["ocaml" "setup.ml" "-install"]
 remove: ["ocamlfind" "remove" "distributed"]
 depends: [
-  "ocaml" {>= "4.02.3"}
+  "ocaml" {>= "4.02.3" & < "5.0"}
   "base-threads"
   "base-unix"
   "lwt" {< "3.0.0"}
diff --git a/packages/distributed/distributed.0.4.0/opam b/packages/distributed/distributed.0.4.0/opam
index bce370edef5..4e89b9fbbec 100644
--- a/packages/distributed/distributed.0.4.0/opam
+++ b/packages/distributed/distributed.0.4.0/opam
@@ -17,7 +17,7 @@ build: [
 install: ["ocaml" "setup.ml" "-install"]
 remove: ["ocamlfind" "remove" "distributed"]
 depends: [
-  "ocaml" {>= "4.02.3"}
+  "ocaml" {>= "4.02.3" & < "5.0"}
   "base-threads"
   "base-unix"
   "lwt" {>= "2.7.0" & < "4.0.0"}
diff --git a/packages/distributed/distributed.0.5.0/opam b/packages/distributed/distributed.0.5.0/opam
index 27c2f1b01c9..53ad5eda1ce 100644
--- a/packages/distributed/distributed.0.5.0/opam
+++ b/packages/distributed/distributed.0.5.0/opam
@@ -12,7 +12,7 @@ build: [
 ]
 
 depends: [
-  "ocaml" {>= "4.02.3"}
+  "ocaml" {>= "4.02.3" & < "5.0"}
   "jbuilder" {>= "1.0+beta16"}
   "base-unix"
 ]
diff --git a/packages/distributed/distributed.0.6.0/opam b/packages/distributed/distributed.0.6.0/opam
index 94ba126a685..bdfb6863c55 100644
--- a/packages/distributed/distributed.0.6.0/opam
+++ b/packages/distributed/distributed.0.6.0/opam
@@ -14,7 +14,7 @@ build: [
 depends: [
   "dune" {>= "1.11.0"}
   "base-unix"  
-  "ocaml" {>= "4.02.3"}
+  "ocaml" {>= "4.02.3" & < "5.0"}
 ]
 
 synopsis: "Library to provide Erlang style distributed computations. This library is inspired by Cloud Haskell"
diff --git a/packages/http/http.6.0.0~alpha0/opam b/packages/http/http.6.0.0~alpha0/opam
index 2b59585b0a8..60df4017979 100644
--- a/packages/http/http.6.0.0~alpha0/opam
+++ b/packages/http/http.6.0.0~alpha0/opam
@@ -22,7 +22,7 @@ bug-reports: "https://github.com/mirage/ocaml-cohttp/issues"
 depends: [
   "dune" {>= "2.9"}
   "ocaml" {>= "4.08"}
-  "ppx_expect" {with-test}
+  "ppx_expect" {with-test & < "v0.17.0"}
   "alcotest" {with-test}
   "base_quickcheck" {with-test}
   "ppx_assert" {with-test}
diff --git a/packages/http/http.6.0.0~alpha1/opam b/packages/http/http.6.0.0~alpha1/opam
index 0712697e1ed..5933a54e8d1 100644
--- a/packages/http/http.6.0.0~alpha1/opam
+++ b/packages/http/http.6.0.0~alpha1/opam
@@ -22,7 +22,7 @@ bug-reports: "https://github.com/mirage/ocaml-cohttp/issues"
 depends: [
   "dune" {>= "3.0"}
   "ocaml" {>= "4.08"}
-  "ppx_expect" {with-test}
+  "ppx_expect" {with-test & < "v0.17.0"}
   "alcotest" {with-test}
   "base_quickcheck" {with-test}
   "ppx_assert" {with-test}
diff --git a/packages/phylogenetics/phylogenetics.0.2.0/opam b/packages/phylogenetics/phylogenetics.0.2.0/opam
index 50b992a90a6..5549e65d14e 100644
--- a/packages/phylogenetics/phylogenetics.0.2.0/opam
+++ b/packages/phylogenetics/phylogenetics.0.2.0/opam
@@ -11,7 +11,7 @@ depends: [
   "angstrom-unix"
   "binning"
   "biotk" {>= "0.2.0"}
-  "core" {>= "v0.15.0"}
+  "core" {>= "v0.15.0" & < "v0.17.0"}
   "dune" {>= "3.6"}
   "gsl"
   "lacaml" {>= "10.0.2"}
diff --git a/packages/ppx_parser/ppx_parser.0.1.1/opam b/packages/ppx_parser/ppx_parser.0.1.1/opam
index b508572c9c0..dfc05294f4b 100644
--- a/packages/ppx_parser/ppx_parser.0.1.1/opam
+++ b/packages/ppx_parser/ppx_parser.0.1.1/opam
@@ -20,7 +20,7 @@ depends: [
   "ocaml" {>= "4.13.0"}
   "dune" {>= "2.9"}
   "ppxlib" {>= "0.27.0"}
-  "alcotest" {with-test}
+  "alcotest" {with-test & >= "1.2.0"}
   "ppx_deriving" {with-test}
   "camlp-streams" {with-test}
   "odoc" {with-doc}
diff --git a/packages/pyml_bindgen/pyml_bindgen.0.1.1/opam b/packages/pyml_bindgen/pyml_bindgen.0.1.1/opam
index dbb41952f5b..0322e9560a3 100644
--- a/packages/pyml_bindgen/pyml_bindgen.0.1.1/opam
+++ b/packages/pyml_bindgen/pyml_bindgen.0.1.1/opam
@@ -10,7 +10,7 @@ depends: [
   "dune" {>= "2.8"}
   "dune" {with-test & < "3.0"}
   "angstrom" {>= "0.15.0"}
-  "base" {>= "v0.12"}
+  "base" {>= "v0.12" & < "v0.17.0"}
   "cmdliner" {>= "1.0"}
   "cmdliner" {with-test & < "1.1.0"}
   "ppx_let" {>= "v0.12"}
diff --git a/packages/pyml_bindgen/pyml_bindgen.0.1.2/opam b/packages/pyml_bindgen/pyml_bindgen.0.1.2/opam
index 4c008d60e0e..dbdb625e9bb 100644
--- a/packages/pyml_bindgen/pyml_bindgen.0.1.2/opam
+++ b/packages/pyml_bindgen/pyml_bindgen.0.1.2/opam
@@ -10,7 +10,7 @@ depends: [
   "dune" {>= "2.8"}
   "dune" {with-test & < "3.0"}
   "angstrom" {>= "0.15.0"}
-  "base" {>= "v0.12"}
+  "base" {>= "v0.12" & < "v0.17.0"}
   "cmdliner" {>= "1.0"}
   "cmdliner" {with-test & < "1.1.0"}
   "ppx_let" {>= "v0.12"}
diff --git a/packages/pyml_bindgen/pyml_bindgen.0.2.0/opam b/packages/pyml_bindgen/pyml_bindgen.0.2.0/opam
index 33794b7d164..996ae710795 100644
--- a/packages/pyml_bindgen/pyml_bindgen.0.2.0/opam
+++ b/packages/pyml_bindgen/pyml_bindgen.0.2.0/opam
@@ -10,7 +10,7 @@ depends: [
   "dune" {>= "2.8"}
   "dune" {with-test & < "3.0"}
   "angstrom" {>= "0.15.0"}
-  "base" {>= "v0.12"}
+  "base" {>= "v0.12" & < "v0.17.0"}
   "cmdliner" {>= "1.0"}
   "cmdliner" {with-test & < "1.1.0"}
   "ppx_let" {>= "v0.12"}
diff --git a/packages/pyml_bindgen/pyml_bindgen.0.3.0/opam b/packages/pyml_bindgen/pyml_bindgen.0.3.0/opam
index 431fe1427f1..8f57b33e717 100644
--- a/packages/pyml_bindgen/pyml_bindgen.0.3.0/opam
+++ b/packages/pyml_bindgen/pyml_bindgen.0.3.0/opam
@@ -9,7 +9,7 @@ bug-reports: "https://github.com/mooreryan/ocaml_python_bindgen/issues"
 depends: [
   "dune" {>= "3.0"}
   "angstrom" {>= "0.15.0"}
-  "base" {>= "v0.12"}
+  "base" {>= "v0.12" & < "v0.17.0"}
   "cmdliner" {>= "1.1.0"}
   "ppx_let" {>= "v0.12"}
   "ppx_sexp_conv" {>= "v0.12"}
diff --git a/packages/qcheck-core/qcheck-core.0.18.1/opam b/packages/qcheck-core/qcheck-core.0.18.1/opam
index 47189c9f735..d0e5e56040e 100644
--- a/packages/qcheck-core/qcheck-core.0.18.1/opam
+++ b/packages/qcheck-core/qcheck-core.0.18.1/opam
@@ -18,7 +18,7 @@ depends: [
   "dune" { >= "2.2" }
   "base-bytes"
   "base-unix"
-  "alcotest" {with-test}
+  "alcotest" {with-test & >= "1.2.0"}
   "odoc" {with-doc}
   "ocaml" {>= "4.08.0"}
 ]
diff --git a/packages/qcheck-core/qcheck-core.0.18/opam b/packages/qcheck-core/qcheck-core.0.18/opam
index 610a094f105..dc5cd18825b 100644
--- a/packages/qcheck-core/qcheck-core.0.18/opam
+++ b/packages/qcheck-core/qcheck-core.0.18/opam
@@ -18,7 +18,7 @@ depends: [
   "dune" { >= "2.2" }
   "base-bytes"
   "base-unix"
-  "alcotest" {with-test}
+  "alcotest" {with-test & >= "1.2.0"}
   "odoc" {with-doc}
   "ocaml" {>= "4.08.0"}
 ]
diff --git a/packages/qcheck-core/qcheck-core.0.19.1/opam b/packages/qcheck-core/qcheck-core.0.19.1/opam
index b59d9ed7764..aeaa41c1b2e 100644
--- a/packages/qcheck-core/qcheck-core.0.19.1/opam
+++ b/packages/qcheck-core/qcheck-core.0.19.1/opam
@@ -18,7 +18,7 @@ depends: [
   "dune" { >= "2.2" }
   "base-bytes"
   "base-unix"
-  "alcotest" {with-test}
+  "alcotest" {with-test & >= "1.2.0"}
   "odoc" {with-doc}
   "ocaml" {>= "4.08.0"}
   "ocaml" {with-test & < "5.0"}
diff --git a/packages/qcheck-core/qcheck-core.0.19/opam b/packages/qcheck-core/qcheck-core.0.19/opam
index 64f36395d86..2b82ea8b63f 100644
--- a/packages/qcheck-core/qcheck-core.0.19/opam
+++ b/packages/qcheck-core/qcheck-core.0.19/opam
@@ -11,7 +11,7 @@ depends: [
   "dune" {>= "2.2"}
   "base-bytes"
   "base-unix"
-  "alcotest" {with-test}
+  "alcotest" {with-test & >= "1.2.0"}
   "odoc" {with-doc}
   "ocaml" {>= "4.08.0"}
 ]
diff --git a/packages/qcheck-core/qcheck-core.0.20/opam b/packages/qcheck-core/qcheck-core.0.20/opam
index beeda800c5b..3769312169a 100644
--- a/packages/qcheck-core/qcheck-core.0.20/opam
+++ b/packages/qcheck-core/qcheck-core.0.20/opam
@@ -11,7 +11,7 @@ depends: [
   "dune" {>= "2.2"}
   "base-bytes"
   "base-unix"
-  "alcotest" {with-test}
+  "alcotest" {with-test & >= "1.2.0"}
   "odoc" {with-doc}
   "ocaml" {>= "4.08.0"}
 ]
diff --git a/packages/qcheck-core/qcheck-core.0.21.1/opam b/packages/qcheck-core/qcheck-core.0.21.1/opam
index afe0c1456eb..9a0ba649a2c 100644
--- a/packages/qcheck-core/qcheck-core.0.21.1/opam
+++ b/packages/qcheck-core/qcheck-core.0.21.1/opam
@@ -18,7 +18,7 @@ depends: [
   "dune" { >= "2.8.0" }
   "base-bytes"
   "base-unix"
-  "alcotest" {with-test}
+  "alcotest" {with-test & >= "1.2.0"}
   "odoc" {with-doc}
   "ocaml" {>= "4.08.0"}
 ]
diff --git a/packages/qcheck-core/qcheck-core.0.21.2/opam b/packages/qcheck-core/qcheck-core.0.21.2/opam
index 50a733b32a4..66c4d3c71b7 100644
--- a/packages/qcheck-core/qcheck-core.0.21.2/opam
+++ b/packages/qcheck-core/qcheck-core.0.21.2/opam
@@ -11,7 +11,7 @@ depends: [
   "dune" {>= "2.8.0"}
   "base-bytes"
   "base-unix"
-  "alcotest" {with-test}
+  "alcotest" {with-test & >= "1.2.0"}
   "odoc" {with-doc}
   "ocaml" {>= "4.08.0"}
 ]
diff --git a/packages/qcheck-core/qcheck-core.0.21.3/opam b/packages/qcheck-core/qcheck-core.0.21.3/opam
index 372a1b97560..cd527a3e3f7 100644
--- a/packages/qcheck-core/qcheck-core.0.21.3/opam
+++ b/packages/qcheck-core/qcheck-core.0.21.3/opam
@@ -17,7 +17,7 @@ build: [
 depends: [
   "dune" { >= "2.8.0" }
   "base-unix"
-  "alcotest" {with-test}
+  "alcotest" {with-test & >= "1.2.0"}
   "odoc" {with-doc}
   "ocaml" {>= "4.08.0"}
 ]
diff --git a/packages/qcheck-core/qcheck-core.0.21/opam b/packages/qcheck-core/qcheck-core.0.21/opam
index 0955012617d..b6d19f29b4f 100644
--- a/packages/qcheck-core/qcheck-core.0.21/opam
+++ b/packages/qcheck-core/qcheck-core.0.21/opam
@@ -11,7 +11,7 @@ depends: [
   "dune" {>= "2.8.0"}
   "base-bytes"
   "base-unix"
-  "alcotest" {with-test}
+  "alcotest" {with-test & >= "1.2.0"}
   "odoc" {with-doc}
   "ocaml" {>= "4.08.0"}
 ]
diff --git a/packages/shuttle/shuttle.0.4.0/opam b/packages/shuttle/shuttle.0.4.0/opam
index cc5c63cc158..feb6efd1828 100644
--- a/packages/shuttle/shuttle.0.4.0/opam
+++ b/packages/shuttle/shuttle.0.4.0/opam
@@ -9,7 +9,7 @@ bug-reports: "https://github.com/anuragsoni/shuttle/issues"
 depends: [
   "dune" {>= "2.8"}
   "ocaml" {>= "4.11.0"}
-  "async" {>= "v0.14"}
+  "async" {>= "v0.14" & < "v0.17.0"}
   "core" {>= "v0.14"}
   "core_unix" {>= "v0.14"}
   "ppx_jane" {>= "v0.14"}
diff --git a/packages/shuttle/shuttle.0.5.0/opam b/packages/shuttle/shuttle.0.5.0/opam
index 5e0647601ab..ebc3bfdc403 100644
--- a/packages/shuttle/shuttle.0.5.0/opam
+++ b/packages/shuttle/shuttle.0.5.0/opam
@@ -9,7 +9,7 @@ bug-reports: "https://github.com/anuragsoni/shuttle/issues"
 depends: [
   "dune" {>= "2.8"}
   "ocaml" {>= "4.11.0"}
-  "async" {>= "v0.14"}
+  "async" {>= "v0.14" & < "v0.17.0"}
   "core" {>= "v0.14"}
   "core_unix" {>= "v0.14"}
   "ppx_jane" {>= "v0.14"}
diff --git a/packages/shuttle/shuttle.0.6.0/opam b/packages/shuttle/shuttle.0.6.0/opam
index 0ff5bb2fea2..8c680999e4a 100644
--- a/packages/shuttle/shuttle.0.6.0/opam
+++ b/packages/shuttle/shuttle.0.6.0/opam
@@ -10,7 +10,7 @@ bug-reports: "https://github.com/anuragsoni/shuttle/issues"
 depends: [
   "dune" {>= "2.8"}
   "ocaml" {>= "4.11.0"}
-  "async" {>= "v0.15.0"}
+  "async" {>= "v0.15.0" & < "v0.17.0"}
   "core" {>= "v0.15.0"}
   "core_unix" {>= "v0.15.0"}
   "ppx_jane" {>= "v0.15.0"}
diff --git a/packages/shuttle/shuttle.0.7.0/opam b/packages/shuttle/shuttle.0.7.0/opam
index c789c578038..1c49c94f994 100644
--- a/packages/shuttle/shuttle.0.7.0/opam
+++ b/packages/shuttle/shuttle.0.7.0/opam
@@ -10,7 +10,7 @@ bug-reports: "https://github.com/anuragsoni/shuttle/issues"
 depends: [
   "dune" {>= "2.8"}
   "ocaml" {>= "4.11.0"}
-  "async" {>= "v0.15.0"}
+  "async" {>= "v0.15.0" & < "v0.17.0"}
   "core" {>= "v0.15.0"}
   "core_unix" {>= "v0.15.0"}
   "ppx_jane" {>= "v0.15.0"}
diff --git a/packages/shuttle/shuttle.0.8.1/opam b/packages/shuttle/shuttle.0.8.1/opam
index 692dff38f3b..49c02de6f8a 100644
--- a/packages/shuttle/shuttle.0.8.1/opam
+++ b/packages/shuttle/shuttle.0.8.1/opam
@@ -10,7 +10,7 @@ bug-reports: "https://github.com/anuragsoni/shuttle/issues"
 depends: [
   "dune" {>= "2.8"}
   "ocaml" {>= "4.11.0"}
-  "async" {>= "v0.15.0"}
+  "async" {>= "v0.15.0" & < "v0.17.0"}
   "core" {>= "v0.15.0"}
   "core_unix" {>= "v0.15.0"}
   "ppx_jane" {>= "v0.15.0"}
diff --git a/packages/shuttle/shuttle.0.9.0/opam b/packages/shuttle/shuttle.0.9.0/opam
index 255f70a384f..c819912ede1 100644
--- a/packages/shuttle/shuttle.0.9.0/opam
+++ b/packages/shuttle/shuttle.0.9.0/opam
@@ -10,7 +10,7 @@ bug-reports: "https://github.com/anuragsoni/shuttle/issues"
 depends: [
   "dune" {>= "2.8"}
   "ocaml" {>= "4.11.0"}
-  "async" {>= "v0.15.0"}
+  "async" {>= "v0.15.0" & < "v0.17.0"}
   "core" {>= "v0.15.0"}
   "core_unix" {>= "v0.15.0"}
   "ppx_jane" {>= "v0.15.0"}
diff --git a/packages/shuttle/shuttle.0.9.1/opam b/packages/shuttle/shuttle.0.9.1/opam
index 8fa2c0cd4da..eedf0f26256 100644
--- a/packages/shuttle/shuttle.0.9.1/opam
+++ b/packages/shuttle/shuttle.0.9.1/opam
@@ -10,7 +10,7 @@ bug-reports: "https://github.com/anuragsoni/shuttle/issues"
 depends: [
   "dune" {>= "2.8"}
   "ocaml" {>= "4.11.0"}
-  "async" {>= "v0.15.0"}
+  "async" {>= "v0.15.0" & < "v0.17.0"}
   "core" {>= "v0.15.0"}
   "core_unix" {>= "v0.15.0"}
   "ppx_jane" {>= "v0.15.0"}
diff --git a/packages/shuttle/shuttle.0.9.2/opam b/packages/shuttle/shuttle.0.9.2/opam
index cc3fefdeeb9..e6214eeb990 100644
--- a/packages/shuttle/shuttle.0.9.2/opam
+++ b/packages/shuttle/shuttle.0.9.2/opam
@@ -9,7 +9,7 @@ bug-reports: "https://github.com/anuragsoni/shuttle/issues"
 depends: [
   "dune" {>= "2.8"}
   "ocaml" {>= "4.11.0"}
-  "async" {>= "v0.15.0"}
+  "async" {>= "v0.15.0" & < "v0.17.0"}
   "core" {>= "v0.15.0"}
   "core_unix" {>= "v0.15.0"}
   "ppx_jane" {>= "v0.15.0"}
diff --git a/packages/shuttle/shuttle.0.9.4/opam b/packages/shuttle/shuttle.0.9.4/opam
index b4598ada4ac..cb7be894544 100644
--- a/packages/shuttle/shuttle.0.9.4/opam
+++ b/packages/shuttle/shuttle.0.9.4/opam
@@ -9,7 +9,7 @@ bug-reports: "https://github.com/anuragsoni/shuttle/issues"
 depends: [
   "dune" {>= "2.8"}
   "ocaml" {>= "4.11.0"}
-  "async" {>= "v0.15.0"}
+  "async" {>= "v0.15.0" & < "v0.17.0"}
   "core" {>= "v0.15.0"}
   "core_unix" {>= "v0.15.0"}
   "ppx_jane" {>= "v0.15.0"}
diff --git a/packages/shuttle_http/shuttle_http.0.10.0/opam b/packages/shuttle_http/shuttle_http.0.10.0/opam
index 9e7a5521383..a66f94415fb 100644
--- a/packages/shuttle_http/shuttle_http.0.10.0/opam
+++ b/packages/shuttle_http/shuttle_http.0.10.0/opam
@@ -10,7 +10,7 @@ homepage: "https://github.com/anuragsoni/shuttle_http"
 bug-reports: "https://github.com/anuragsoni/shuttle_http/issues"
 depends: [
   "dune" {>= "2.8"}
-  "async" {>= "v0.16.0"}
+  "async" {>= "v0.16.0" & < "v0.17.0"}
   "async_ssl" {>= "v0.16.0"}
   "core" {>= "v0.16.0"}
   "jane_rope" {>= "v0.16.0"}
diff --git a/packages/shuttle_http/shuttle_http.0.10.1/opam b/packages/shuttle_http/shuttle_http.0.10.1/opam
index 3ad13e066ce..8542efcf3f8 100644
--- a/packages/shuttle_http/shuttle_http.0.10.1/opam
+++ b/packages/shuttle_http/shuttle_http.0.10.1/opam
@@ -10,7 +10,7 @@ homepage: "https://github.com/anuragsoni/shuttle_http"
 bug-reports: "https://github.com/anuragsoni/shuttle_http/issues"
 depends: [
   "dune" {>= "2.8"}
-  "async" {>= "v0.16.0"}
+  "async" {>= "v0.16.0" & < "v0.17.0"}
   "async_ssl" {>= "v0.16.0"}
   "core" {>= "v0.16.0"}
   "jane_rope" {>= "v0.16.0"}
diff --git a/packages/shuttle_http/shuttle_http.0.11.0/opam b/packages/shuttle_http/shuttle_http.0.11.0/opam
index 8dba7ecd9bb..b8a6a96add0 100644
--- a/packages/shuttle_http/shuttle_http.0.11.0/opam
+++ b/packages/shuttle_http/shuttle_http.0.11.0/opam
@@ -10,7 +10,7 @@ homepage: "https://sr.ht/~soni/shuttle_http"
 bug-reports: "https://todo.sr.ht/~soni/shuttle_http"
 depends: [
   "dune" {>= "3.1"}
-  "async" {>= "v0.16.0"}
+  "async" {>= "v0.16.0" & < "v0.17.0"}
   "async_ssl" {>= "v0.16.0"}
   "async_websocket" {>= "v0.16.0"}
   "core" {>= "v0.16.0"}