diff --git a/pkgs/development/python-modules/pyvoro/default.nix b/pkgs/development/python-modules/pyvoro/default.nix
index 802ad73a6411..595fa345f303 100644
--- a/pkgs/development/python-modules/pyvoro/default.nix
+++ b/pkgs/development/python-modules/pyvoro/default.nix
@@ -20,5 +20,15 @@ buildPythonPackage rec {
     description = "2D and 3D Voronoi tessellations: a python entry point for the voro++ library";
     license = licenses.mit;
     maintainers = [ ];
+
+    # Cython generated code is vendored directly and no longer compatible with
+    # newer versions of the CPython C API.
+    #
+    # Upstream explicitly removed the Cython source files from the source
+    # distribution, making it impossible for us to force-compile them:
+    # https://github.com/joe-jordan/pyvoro/commit/922bba6db32d44c2e1825228627a25aa891f9bc1
+    #
+    # No upstream activity since 2014.
+    broken = true;
   };
 }