diff --git a/nixos/tests/mitmproxy.nix b/nixos/tests/mitmproxy.nix
index 1a3d98d7fcf2..334085463a20 100644
--- a/nixos/tests/mitmproxy.nix
+++ b/nixos/tests/mitmproxy.nix
@@ -86,7 +86,7 @@ in
     ''
       def curl(command: str, proxy: bool = False):
           if proxy:
-              command = "curl --proxy 127.0.0.1:8080 --cacert ~/.mitmproxy/mitmproxy-ca-cert.pem " + command
+              command = "curl --proxy 127.0.0.1:8080 --cacert ~/.mitmproxy/mitmproxy-ca.pem " + command
           else:
               command = "curl " + command
           return machine.succeed(command)