diff --git a/tools/grid_proteus.py b/tools/grid_proteus.py
index 7a875dc1..d162671a 100755
--- a/tools/grid_proteus.py
+++ b/tools/grid_proteus.py
@@ -265,7 +265,7 @@ def run(self,num_threads:int,test_run:bool=False):
         num_threads = min(num_threads, self.size)
 
         # do not use more threads than are available
-        num_threads = min(num_threads, os.process_cpu_count())
+        num_threads = min(num_threads, os.cpu_count())
 
         # Print warning
         if not test_run: