diff --git a/numpyro/infer/hmc_gibbs.py b/numpyro/infer/hmc_gibbs.py
index 2e9498e99..57a83151c 100644
--- a/numpyro/infer/hmc_gibbs.py
+++ b/numpyro/infer/hmc_gibbs.py
@@ -186,6 +186,11 @@ def potential_fn(z_gibbs, z_hmc):
 
         return HMCGibbsState(z, hmc_state, rng_key)
 
+    def __getstate__(self):
+        state = self.__dict__.copy()
+        state["_prototype_trace"] = None
+        return state
+
 
 def _discrete_gibbs_proposal_body_fn(
     z_init_flat, unravel_fn, pe_init, potential_fn, idx, i, val
diff --git a/numpyro/infer/mixed_hmc.py b/numpyro/infer/mixed_hmc.py
index 863418602..726d18c4c 100644
--- a/numpyro/infer/mixed_hmc.py
+++ b/numpyro/infer/mixed_hmc.py
@@ -307,4 +307,6 @@ def body_fn(i, vals):
     def __getstate__(self):
         state = self.__dict__.copy()
         state["_wa_update"] = None
+        state["_prototype_trace"] = None
+        state["_support_sizes_flat"] = None
         return state