diff --git a/pkgs/python-packages/pyln-proto/default.nix b/pkgs/python-packages/pyln-proto/default.nix
index e66de6d..80303a2 100644
--- a/pkgs/python-packages/pyln-proto/default.nix
+++ b/pkgs/python-packages/pyln-proto/default.nix
@@ -29,6 +29,7 @@ buildPythonPackage rec {
   postUnpack = "sourceRoot=$sourceRoot/contrib/pyln-proto";
   postPatch = ''
     sed -i '
+      s|pycparser==2.20|pycparser~=2.20|
       s|coincurve ~= 13.0|coincurve == 15.0.0|
       s|base58 ~= 2.0.1|base58 == 2.1.0|
       s|mypy==0.790|mypy == 0.812|