diff --git a/pkgs/development/compilers/dart/package-source-builders/rhttp/default.nix b/pkgs/development/compilers/dart/package-source-builders/rhttp/default.nix
index 0be6f3f9f761..5bf7e2eb4497 100644
--- a/pkgs/development/compilers/dart/package-source-builders/rhttp/default.nix
+++ b/pkgs/development/compilers/dart/package-source-builders/rhttp/default.nix
@@ -35,6 +35,7 @@ let
         _0_9_8 = "sha256-cwb1wYVXOE5YABlMxUDt+OMlDpIlipqeNI7ZFAGHCqo=";
         _0_10_0 = "sha256-2SpAj53XvZXKRpMzFXJGcx7E2TlMUD+ooHkFwg/9fe4=";
         _0_11_0 = "sha256-sngh5k9GoCZhnIFTpnAVHZjxTcOv+Ui6pJ2cFyriL84=";
+        _0_12_0 = "sha256-W2DcBy1n73nR2oZIQcFt6A+NElQWtfEtKB1YIweQUVo=";
       }
       .${"_" + (lib.replaceStrings [ "." ] [ "_" ] version)} or (throw ''
         Unsupported version of pub 'rhttp': '${version}'