diff --git a/pkgs/development/python-modules/pyorthanc/default.nix b/pkgs/development/python-modules/pyorthanc/default.nix
index 5a537f7f8b28..678c66d29b22 100644
--- a/pkgs/development/python-modules/pyorthanc/default.nix
+++ b/pkgs/development/python-modules/pyorthanc/default.nix
@@ -3,6 +3,7 @@
 , fetchFromGitHub
 , pythonOlder
 , pytestCheckHook
+, pythonRelaxDepsHook
 , poetry-core
 , httpx
 , pydicom
@@ -22,10 +23,14 @@ buildPythonPackage rec {
     hash = "sha256-RZJ7BuQRJ+yaHFv9iq4uFvMtH8NvGvmpjmgmyvw9rGk=";
   };
 
-  nativeBuildInputs = [ poetry-core ];
+  nativeBuildInputs = [ pythonRelaxDepsHook poetry-core ];
 
   propagatedBuildInputs = [ httpx pydicom ];
 
+  pythonRelaxDeps = [
+    "httpx"
+  ];
+
   doCheck = false;  # requires orthanc server (not in Nixpkgs)
 
   pythonImportsCheck = [