diff --git a/pkgs/applications/misc/eureka-ideas/default.nix b/pkgs/applications/misc/eureka-ideas/default.nix
index ee15f31632cb..45e36010906b 100644
--- a/pkgs/applications/misc/eureka-ideas/default.nix
+++ b/pkgs/applications/misc/eureka-ideas/default.nix
@@ -30,7 +30,7 @@ rustPlatform.buildRustPackage rec {
     Security
   ];
 
-  dontUseCargoParallelTests = true;
+  useNextest = true;
 
   meta = with lib; {
     description = "CLI tool to input and store your ideas without leaving the terminal";
diff --git a/pkgs/applications/networking/browsers/castor/default.nix b/pkgs/applications/networking/browsers/castor/default.nix
index 5a0a7f0d215b..6a898fb0c95d 100644
--- a/pkgs/applications/networking/browsers/castor/default.nix
+++ b/pkgs/applications/networking/browsers/castor/default.nix
@@ -40,8 +40,7 @@ rustPlatform.buildRustPackage rec {
 
   postInstall = "make PREFIX=$out copy-data";
 
-  # Sometimes tests fail when run in parallel
-  dontUseCargoParallelThreads = true;
+  useNextest = true;
 
   meta = with lib; {
     description = "A graphical client for plain-text protocols written in Rust with GTK. It currently supports the Gemini, Gopher and Finger protocols";