diff --git a/pkgs/by-name/ag/agent-browser/package.nix b/pkgs/by-name/ag/agent-browser/package.nix
index 9e0803bd9f2b..61511f9f835f 100644
--- a/pkgs/by-name/ag/agent-browser/package.nix
+++ b/pkgs/by-name/ag/agent-browser/package.nix
@@ -103,12 +103,8 @@ rustPlatform.buildRustPackage (finalAttrs: {
     writableTmpDirAsHomeHook
   ];
 
-  # Flaky test: reads the AGENT_BROWSER_CDP env variable without using the
-  # shared test lock.
-  checkFlags = [
-    "--skip"
-    "native::actions::tests::test_execute_unknown_command"
-  ];
+  # Some tests use a shared state that makes them flaky when run concurrently.
+  dontUseCargoParallelTests = true;
 
   __darwinAllowLocalNetworking = true;