diff --git a/pkgs/development/python-modules/class-doc/default.nix b/pkgs/development/python-modules/class-doc/default.nix
index 937a94c953b8..432df1f674ee 100644
--- a/pkgs/development/python-modules/class-doc/default.nix
+++ b/pkgs/development/python-modules/class-doc/default.nix
@@ -1,6 +1,7 @@
 { lib
 , buildPythonPackage
 , fetchFromGitHub
+, fetchpatch
 , poetry-core
 , more-itertools
 , pytestCheckHook
@@ -13,21 +14,24 @@ buildPythonPackage rec {
 
   src = fetchFromGitHub {
     owner = "danields761";
-    repo = "${pname}";
+    repo = pname;
     rev = "9b122d85ce667d096ebee75a49350bbdbd48686d"; # no 0.2.6 version tag
     hash = "sha256-4Sn/TuBvBpl1nvJBg327+sVrjGavkYKEYP32DwLWako=";
   };
 
+  patches = [
+    # https://github.com/danields761/class-doc/pull/2
+    (fetchpatch {
+      name = "poetry-to-poetry-core.patch";
+      url = "https://github.com/danields761/class-doc/commit/03b224ad0a6190c30e4932fa2ccd4a7f0c5c4b5d.patch";
+      hash = "sha256-shWPRaZkvtJ1Ae17aCOm6eLs905jxwq84SWOrChEs7M=";
+    })
+  ];
+
   nativeBuildInputs = [
     poetry-core
   ];
 
-  postPatch = ''
-    substituteInPlace pyproject.toml --replace \
-      "poetry.masonry.api" \
-      "poetry.core.masonry.api"
-  '';
-
   propagatedBuildInputs = [
     more-itertools
   ];