diff --git a/pkgs/development/tools/ocaml/ocamlformat/default.nix b/pkgs/development/tools/ocaml/ocamlformat/default.nix
index 096fe1b4324a..5847f18ba3d9 100644
--- a/pkgs/development/tools/ocaml/ocamlformat/default.nix
+++ b/pkgs/development/tools/ocaml/ocamlformat/default.nix
@@ -68,5 +68,9 @@ rec {
     version = "0.20.1";
   };
 
-  ocamlformat = ocamlformat_0_20_1;
+  ocamlformat_0_21_0 = mkOCamlformat {
+    version = "0.21.0";
+  };
+
+  ocamlformat = ocamlformat_0_21_0;
 }
diff --git a/pkgs/development/tools/ocaml/ocamlformat/generic.nix b/pkgs/development/tools/ocaml/ocamlformat/generic.nix
index 517ca6585fe1..7eee57e9abcc 100644
--- a/pkgs/development/tools/ocaml/ocamlformat/generic.nix
+++ b/pkgs/development/tools/ocaml/ocamlformat/generic.nix
@@ -25,6 +25,7 @@ let src =
       "0.19.0" = "0ihgwl7d489g938m1jvgx8azdgq9f5np5mzqwwya797hx2m4dz32";
       "0.20.0" = "sha256-JtmNCgwjbCyUE4bWqdH5Nc2YSit+rekwS43DcviIfgk=";
       "0.20.1" = "sha256-fTpRZFQW+ngoc0T6A69reEUAZ6GmHkeQvxspd5zRAjU=";
+      "0.21.0" = "sha256-KhgX9rxYH/DM6fCqloe4l7AnJuKrdXSe6Y1XY3BXMy0=";
     }."${version}";
   };
   ocamlPackages =
@@ -60,7 +61,7 @@ buildDunePackage {
     if lib.versionAtLeast version "0.20.0"
     then [
       base
-      cmdliner
+      (if lib.versionAtLeast version "0.21.0" then cmdliner_1_1 else cmdliner_1_0)
       dune-build-info
       either
       fix
@@ -78,7 +79,7 @@ buildDunePackage {
     else if lib.versionAtLeast version "0.19.0"
     then [
       base
-      cmdliner
+      cmdliner_1_0
       fpath
       re
       stdio
@@ -94,7 +95,7 @@ buildDunePackage {
     else if lib.versionAtLeast version "0.18.0"
     then [
       base
-      cmdliner
+      cmdliner_1_0
       fpath
       odoc
       re
@@ -112,7 +113,7 @@ buildDunePackage {
     else if lib.versionAtLeast version "0.17.0"
     then [
       base
-      cmdliner
+      cmdliner_1_0
       fpath
       odoc
       re
@@ -131,7 +132,7 @@ buildDunePackage {
     else if lib.versionAtLeast version "0.15.1"
     then [
       base
-      cmdliner
+      cmdliner_1_0
       fpath
       odoc
       re
@@ -148,7 +149,7 @@ buildDunePackage {
     else if lib.versionAtLeast version "0.14"
     then [
       base
-      cmdliner
+      cmdliner_1_0
       fpath
       ocaml-migrate-parsetree
       odoc
@@ -161,7 +162,7 @@ buildDunePackage {
       menhirSdk
     ] else [
       base
-      cmdliner
+      cmdliner_1_0
       fpath
       ocaml-migrate-parsetree
       odoc
@@ -178,4 +179,3 @@ buildDunePackage {
     license = lib.licenses.mit;
   };
 }
-
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 5ebb7608596b..d7c7cf7cadf6 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -13570,7 +13570,7 @@ with pkgs;
     ocamlformat_0_11_0 ocamlformat_0_12 ocamlformat_0_13_0 ocamlformat_0_14_0
     ocamlformat_0_14_1 ocamlformat_0_14_2 ocamlformat_0_14_3 ocamlformat_0_15_0
     ocamlformat_0_15_1 ocamlformat_0_16_0 ocamlformat_0_17_0 ocamlformat_0_18_0
-    ocamlformat_0_19_0 ocamlformat_0_20_0 ocamlformat_0_20_1;
+    ocamlformat_0_19_0 ocamlformat_0_20_0 ocamlformat_0_20_1 ocamlformat_0_21_0;
 
   orc = callPackage ../development/compilers/orc { };