diff --git a/rowhammer_tester/targets/common.py b/rowhammer_tester/targets/common.py
index 3d583aabd..de49a7f8c 100644
--- a/rowhammer_tester/targets/common.py
+++ b/rowhammer_tester/targets/common.py
@@ -554,7 +554,7 @@ def get_sim_kwargs(args, interface='litex-sim'):
 class LiteDRAMSettingsEncoder(json.JSONEncoder):
     def default(self, o):
         if isinstance(o, (ControllerSettings, GeomSettings, PhySettings, TimingSettings)):
-            ignored = ['self', 'refresh_cls']
+            ignored = ['self', 'refresh_cls', 'is_rdimm']
             return {k: v for k, v in vars(o).items() if k not in ignored}
         elif isinstance(o, Signal) and isinstance(o.reset, Constant):
             return o.reset