diff --git a/pkgs/development/python-modules/sphinxcontrib-openapi/default.nix b/pkgs/development/python-modules/sphinxcontrib-openapi/default.nix
index c85d967222e36..fbdeb9ae00a35 100644
--- a/pkgs/development/python-modules/sphinxcontrib-openapi/default.nix
+++ b/pkgs/development/python-modules/sphinxcontrib-openapi/default.nix
@@ -1,26 +1,46 @@
 { lib
 , buildPythonPackage
-, fetchPypi
+, deepmerge
+, fetchFromGitHub
+, fetchpatch
 , isPy27
 , setuptools-scm
-, m2r
-, pyyaml
 , jsonschema
+, picobox
+, pyyaml
+, sphinx-mdinclude
 , sphinxcontrib_httpdomain
 }:
 
 buildPythonPackage rec {
   pname = "sphinxcontrib-openapi";
-  version = "0.7.0";
+  version = "unstable-2022-08-26";
   disabled = isPy27;
 
-  src = fetchPypi {
-    inherit pname version;
-    sha256 = "1c1bd10d7653912c59a42f727c62cbb7b75f7905ddd9ccc477ebfd1bc69f0cf3";
+  # Switch to Cilums' fork of openapi, which uses m2r instead of mdinclude,
+  # as m2r is unmaintained and incompatible with the version of mistune.
+  # See
+  # https://github.com/cilium/cilium/commit/b9862461568dd41d4dc8924711d4cc363907270b and
+  # https://github.com/cilium/openapi/commit/cd829a05caebd90b31e325d4c9c2714b459d135f
+  # for details.
+  src = fetchFromGitHub {
+    owner = "cilium";
+    repo = "openapi";
+    rev = "0ea3332fa6482114f1a8248a32a1eacb61aebb69";
+    hash = "sha256-a/oVMg9gGTD+NClfpC2SpjbY/mIcZEVLLOR0muAg5zY=";
   };
 
   nativeBuildInputs = [ setuptools-scm ];
-  propagatedBuildInputs = [ pyyaml jsonschema m2r sphinxcontrib_httpdomain ];
+  propagatedBuildInputs = [
+    deepmerge
+    jsonschema
+    picobox
+    pyyaml
+    sphinx-mdinclude
+    sphinxcontrib_httpdomain
+  ];
+
+  SETUPTOOLS_SCM_PRETEND_VERSION = version;
 
   doCheck = false;
 
@@ -29,5 +49,4 @@ buildPythonPackage rec {
     description = "OpenAPI (fka Swagger) spec renderer for Sphinx";
     license = licenses.bsd0;
   };
-
 }