diff --git a/CHANGES.md b/CHANGES.md
index 9ed07f6c..625c1238 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,4 +1,4 @@
-2.9.0 (2022-06-10)
+2.9.1 (2022-06-10)
 ------------------
 
 * atdgen: update `abstract` type validation to accept all input by default (#301)
diff --git a/atdgen-runtime.opam b/atdgen-runtime.opam
index 1f31eec1..c53626d2 100644
--- a/atdgen-runtime.opam
+++ b/atdgen-runtime.opam
@@ -2,7 +2,7 @@
 opam-version: "2.0"
 synopsis: "Runtime library for code generated by atdgen"
 description: """
-This package should be used only in conjunction with the stdgen code
+This package should be used only in conjunction with the atdgen code
 generator"""
 maintainer: [
   "Louis Roché <louis@louisroche.net>"
@@ -65,7 +65,7 @@ bug-reports: "https://github.com/ahrefs/atd/issues"
 depends: [
   "dune" {>= "2.8"}
   "ocaml" {>= "4.08"}
-  "yojson" {>= "1.7.0"}
+  "yojson" {>= "1.7.0" & < "2.0.0"}
   "biniou" {>= "1.0.6"}
   "camlp-streams"
   "odoc" {with-doc}
diff --git a/atdgen.opam b/atdgen.opam
index 7c696428..734fe904 100644
--- a/atdgen.opam
+++ b/atdgen.opam
@@ -77,7 +77,7 @@ depends: [
   "atdgen-runtime" {>= "2.1.0"}
   "atdgen-codec-runtime" {with-test}
   "biniou" {>= "1.0.6"}
-  "yojson" {>= "1.7.0"}
+  "yojson" {>= "1.7.0" & < "2.0.0"}
   "odoc" {with-doc}
   "re"
 ]
diff --git a/dune-project b/dune-project
index eb823352..b522fd32 100644
--- a/dune-project
+++ b/dune-project
@@ -99,7 +99,7 @@ formats. "))
   (atdgen-runtime (>= 2.1.0))
   (atdgen-codec-runtime :with-test)
   (biniou (>= 1.0.6))
-  (yojson (>= 1.7.0))
+  (yojson (and (>= 1.7.0) (< 2.0.0)))
   (odoc :with-doc)
   re
  )
@@ -119,11 +119,11 @@ Atdgen’s source code."))
  (name atdgen-runtime)
  (synopsis "Runtime library for code generated by atdgen")
  (description "\
-This package should be used only in conjunction with the stdgen code
+This package should be used only in conjunction with the atdgen code
 generator")
  (depends
   (ocaml (>= 4.08))
-  (yojson (>= 1.7.0))
+  (yojson (and (>= 1.7.0) (< 2.0.0)))
   (biniou (>= 1.0.6))
   camlp-streams
   (odoc :with-doc)))