diff --git a/packages/cfstream/cfstream.1.3.1/opam b/packages/cfstream/cfstream.1.3.1/opam
index f8341267f4e6..630bf010bdb7 100644
--- a/packages/cfstream/cfstream.1.3.1/opam
+++ b/packages/cfstream/cfstream.1.3.1/opam
@@ -2,7 +2,7 @@ opam-version: "2.0"
 homepage: "https://github.com/biocaml/cfstream"
 dev-repo: "git+https://github.com/biocaml/cfstream.git"
 bug-reports: "https://github.com/biocaml/cfstream/issues"
-license: "LGPL + linking exception"
+license: "LGPL-2.1-or-later WITH OCaml-LGPL-linking-exception"
 maintainer: "Ashish Agarwal <agarwal1975@gmail.com>"
 synopsis: "Stream operations in the style of Core's API"
 authors: [
@@ -18,7 +18,7 @@ build: [
 depends: [
   "ocaml" {>= "4.04.1" & < "5.0.0"}
   "dune"
-  "core_kernel" {>= "v0.11.0"}
+  "core_kernel" {>= "v0.11.0" & < "v0.16"}
   "conf-m4" {build}
   "ounit" {with-test}
 ]
diff --git a/packages/cfstream/cfstream.1.3.2/opam b/packages/cfstream/cfstream.1.3.2/opam
index c2bf2c77ba09..accdb2fb9368 100644
--- a/packages/cfstream/cfstream.1.3.2/opam
+++ b/packages/cfstream/cfstream.1.3.2/opam
@@ -21,7 +21,7 @@ run-test: [
 depends: [
   "ocaml" {>= "4.04.1"}
   "dune" {>= "1.0"}
-  "core_kernel" {>= "v0.11.0"}
+  "core_kernel" {>= "v0.11.0" < "v0.16"}
   "camlp-streams" {>= "5.0.1"}
   "conf-m4"
   "ounit" {with-test}
diff --git a/packages/csvfields/csvfields.v0.15.0/opam b/packages/csvfields/csvfields.v0.15.0/opam
index b057df3b7025..9705040807a3 100644
--- a/packages/csvfields/csvfields.v0.15.0/opam
+++ b/packages/csvfields/csvfields.v0.15.0/opam
@@ -10,7 +10,7 @@ build: [
   ["dune" "build" "-p" name "-j" jobs]
 ]
 depends: [
-  "ocaml"    {>= "4.08.0"}
+  "ocaml"    {>= "4.08.0" & < "5.0"}
   "core"     {>= "v0.15" & < "v0.16"}
   "ppx_jane" {>= "v0.15" & < "v0.16"}
   "sexplib"  {>= "v0.15" & < "v0.16"}