diff --git a/blackjax/util.py b/blackjax/util.py
index 600a7a961..02c27e51c 100644
--- a/blackjax/util.py
+++ b/blackjax/util.py
@@ -209,7 +209,7 @@ def one_step(average_and_state, xs, return_state):
         _, rng_key = xs
         average, state = average_and_state
         state, info = inference_algorithm.step(rng_key, state)
-        average = streaming_average(expectation(state), average)
+        average = streaming_average(expectation(transform(state)), average)
         if return_state:
             return (average, state), (transform(state), info)
         else:
@@ -222,7 +222,7 @@ def one_step(average_and_state, xs, return_state):
 
     xs = (jnp.arange(num_steps), keys)
     ((_, average), final_state), history = lax.scan(
-        one_step, ((0, expectation(initial_state)), initial_state), xs
+        one_step, ((0, expectation(transform(initial_state))), initial_state), xs
     )
 
     if not return_state_history:
@@ -236,10 +236,8 @@ def streaming_average(expectation, streaming_avg, weight=1.0, zero_prevention=0.
     """Compute the streaming average of a function O(x) using a weight.
     Parameters:
     ----------
-        O
-            function to be averaged
-        x
-            current state
+        expectation
+            the value of the expectation at the current timestep
         streaming_avg
             tuple of (total, average) where total is the sum of weights and average is the current average
         weight
diff --git a/tests/test_util.py b/tests/test_util.py
index 83955acd7..1f03498dd 100644
--- a/tests/test_util.py
+++ b/tests/test_util.py
@@ -55,7 +55,7 @@ def logdensity_fn(x):
             inference_algorithm=alg,
             num_steps=50,
             progress_bar=False,
-            expectation=lambda x: x.position,
+            expectation=lambda x: x,
             transform=lambda x: x.position,
             return_state_history=True,
         )
@@ -66,7 +66,7 @@ def logdensity_fn(x):
             inference_algorithm=alg,
             num_steps=50,
             progress_bar=False,
-            expectation=lambda x: x.position,
+            expectation=lambda x: x,
             transform=lambda x: x.position,
             return_state_history=False,
         )