diff --git a/worldbuild-runner.py b/worldbuild-runner.py
index 5180d9f..6b101ea 100755
--- a/worldbuild-runner.py
+++ b/worldbuild-runner.py
@@ -120,7 +120,7 @@ while running:
 			print("Running:       " + str(l.run_count))
 			print("Shutting down: " + str(l.stop_count))
 		else:
-			match = re.match("(set workers) ([0-9]?)", cmd)
+			match = re.match("(set workers) ([0-9]+)", cmd)
 			if match != None:
 				if match.group(1) == "set workers":
 					l.set_proc_count(int(match.group(2)))