diff --git a/actionpack/test/abstract_unit.rb b/actionpack/test/abstract_unit.rb
index 987ef7de1f..4e17d57dad 100644
--- a/actionpack/test/abstract_unit.rb
+++ b/actionpack/test/abstract_unit.rb
@@ -495,5 +495,5 @@ end
 
 if ActiveSupport::Testing::Isolation.forking_env? && PROCESS_COUNT > 0
   # Use N processes (N defaults to 4)
-  Minitest.parallel_executor = ForkingExecutor.new((ENV['N'] || 4).to_i)
+  Minitest.parallel_executor = ForkingExecutor.new(PROCESS_COUNT)
 end