diff --git a/trieste/acquisition/optimizer.py b/trieste/acquisition/optimizer.py
index 5a8337296a..7eacec596e 100644
--- a/trieste/acquisition/optimizer.py
+++ b/trieste/acquisition/optimizer.py
@@ -388,9 +388,7 @@ def improvements() -> tf.Tensor:
                 if V == 1:
                     logging.scalar("spo_improvement_on_initial_samples", improvements)
                 else:
-                    logging.histogram(
-                        "spo_improvement_on_initial_samples_across_subspaces", improvements
-                    )
+                    logging.histogram("spo_improvements_on_initial_samples", improvements)
 
         best_run_ids = tf.math.argmax(fun_values, axis=0)  # [V]
         chosen_points = tf.gather(