diff --git a/pkgs/development/python-modules/swisshydrodata/default.nix b/pkgs/development/python-modules/swisshydrodata/default.nix
index c805abb98a98..4d7d159401bd 100644
--- a/pkgs/development/python-modules/swisshydrodata/default.nix
+++ b/pkgs/development/python-modules/swisshydrodata/default.nix
@@ -3,9 +3,11 @@
   buildPythonPackage,
   fetchFromGitHub,
   pytestCheckHook,
+  pytest-cov-stub,
   pythonOlder,
   requests-mock,
   requests,
+  aiohttp,
   setuptools,
 }:
 
@@ -25,10 +27,14 @@ buildPythonPackage rec {
 
   build-system = [ setuptools ];
 
-  dependencies = [ requests ];
+  dependencies = [
+    requests
+    aiohttp
+  ];
 
   nativeCheckInputs = [
     pytestCheckHook
+    pytest-cov-stub
     requests-mock
   ];