diff --git a/pkgs/development/python-modules/universal-silabs-flasher/default.nix b/pkgs/development/python-modules/universal-silabs-flasher/default.nix
index 27c60f8db34e..c415b0d11680 100644
--- a/pkgs/development/python-modules/universal-silabs-flasher/default.nix
+++ b/pkgs/development/python-modules/universal-silabs-flasher/default.nix
@@ -62,6 +62,11 @@ buildPythonPackage rec {
     pytest-timeout
   ];
 
+  disabledTests = [
+    # timing sensitive
+    "test_xmodem_happy_path"
+  ];
+
   pythonImportsCheck = [ "universal_silabs_flasher" ];
 
   meta = {