2 files changed, 6 insertions, 2 deletions
diff --git a/sim/gdbstub.py b/sim/gdbstub.py
index 75c15cb..c01a4a7 100644
--- a/sim/gdbstub.py
+++ b/sim/gdbstub.py
@@ -1,5 +1,6 @@
 import sys, socket
 
+cycles = None
 start_halted = True
 
 def init():
diff --git a/sim/sim.py b/sim/sim.py
index be846fb..b0a194a 100755
--- a/sim/sim.py
+++ b/sim/sim.py
@@ -275,13 +275,16 @@ prelude.update({k: v for k, v in all_regs})
 module.__dict__.update(prelude)
 spec.loader.exec_module(module)
 
-cycles = module_get('cycles', 1024)
 mem_dumps = module_get('mem_dumps', [])
 
 if init := module_get('init'):
     init()
 
-exec_args = [verilated, '--headless', '--no-tty', '--cycles', str(cycles), '--dump-regs']
+exec_args = [verilated, '--headless', '--no-tty', '--dump-regs']
+
+cycles = module_get('cycles', 1024)
+if cycles is not None:
+    exec_args.extend(['--cycles', str(cycles)])
 
 for rng in mem_dumps:
     length = rng.stop - rng.start