diff --git a/augur/application/cli/backend.py b/augur/application/cli/backend.py
index ac70eb534b..c083263f3f 100644
--- a/augur/application/cli/backend.py
+++ b/augur/application/cli/backend.py
@@ -165,7 +165,7 @@ def determine_worker_processes(ratio,maximum):
         sleep_time += 6
 
         #60% of estimate, Maximum value of 45
-        core_num_processes = determine_worker_processes(.35 45)
+        core_num_processes = determine_worker_processes(.35, 45)
         logger.info(f"Starting core worker processes with concurrency={core_num_processes}")
         core_worker = f"celery -A augur.tasks.init.celery_app.celery_app worker -l info --concurrency={core_num_processes} -n core:{uuid.uuid4().hex}@%h"
         process_list.append(subprocess.Popen(core_worker.split(" ")))