diff --git a/blackjax/smc/adaptive_tempered.py b/blackjax/smc/adaptive_tempered.py
index b8a611606..10fb194fa 100644
--- a/blackjax/smc/adaptive_tempered.py
+++ b/blackjax/smc/adaptive_tempered.py
@@ -130,7 +130,8 @@ def as_top_level_api(
     mcmc_init_fn
         The MCMC init function used to build a MCMC state from a particle position.
     mcmc_parameters
-        The parameters of the MCMC step function.
+        The parameters of the MCMC step function.  Parameters with leading dimension
+        length of 1 are shared amongst the particles.
     resampling_fn
         The function used to resample the particles.
     target_ess
diff --git a/blackjax/smc/tempered.py b/blackjax/smc/tempered.py
index ca41cc39f..43b83d034 100644
--- a/blackjax/smc/tempered.py
+++ b/blackjax/smc/tempered.py
@@ -109,6 +109,9 @@ def kernel(
             Current state of the tempered SMC algorithm
         lmbda
             Current value of the tempering parameter
+        mcmc_parameters
+            The parameters of the MCMC step function.  Parameters with leading dimension
+            length of 1 are shared amongst the particles.
 
         Returns
         -------
@@ -120,12 +123,13 @@ def kernel(
         """
         delta = lmbda - state.lmbda
 
-        shared_mcmc_parameters = {
-            k: v[0, ...] for k, v in mcmc_parameters.items() if v.shape[0] == 1
-        }
-        unshared_mcmc_parameters = {
-            k: v for k, v in mcmc_parameters.items() if v.shape[0] != 1
-        }
+        shared_mcmc_parameters = {}
+        unshared_mcmc_parameters = {}
+        for k, v in mcmc_parameters.items():
+            if v.shape[0] == 1:
+                shared_mcmc_parameters[k] = v[0, ...]
+            else:
+                unshared_mcmc_parameters[k] = v
 
         def log_weights_fn(position: ArrayLikeTree) -> float:
             return delta * loglikelihood_fn(position)
@@ -188,7 +192,8 @@ def as_top_level_api(
     mcmc_init_fn
         The MCMC init function used to build a MCMC state from a particle position.
     mcmc_parameters
-        The parameters of the MCMC step function.
+        The parameters of the MCMC step function.  Parameters with leading dimension
+        length of 1 are shared amongst the particles.
     resampling_fn
         The function used to resample the particles.
     num_mcmc_steps