diff --git a/pyproject.toml b/pyproject.toml
index 51efe1f585..e053da9efe 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -178,6 +178,7 @@ markers = [
     "widgets",
     "sortingcomponents",
     "streaming_extractors: extractors that require streaming such as ross and fsspec",
+    "ros3_test"
 ]
 filterwarnings =[
     'ignore:.*distutils Version classes are deprecated.*:DeprecationWarning',
diff --git a/src/spikeinterface/sortingcomponents/clustering/merge.py b/src/spikeinterface/sortingcomponents/clustering/merge.py
index 1ed51fb04f..24ec923f06 100644
--- a/src/spikeinterface/sortingcomponents/clustering/merge.py
+++ b/src/spikeinterface/sortingcomponents/clustering/merge.py
@@ -7,7 +7,6 @@
 import scipy.spatial
 from sklearn.decomposition import PCA
 from sklearn.discriminant_analysis import LinearDiscriminantAnalysis
-from hdbscan import HDBSCAN
 
 import numpy as np
 import networkx as nx
diff --git a/src/spikeinterface/sortingcomponents/clustering/split.py b/src/spikeinterface/sortingcomponents/clustering/split.py
index 9418e8efbe..55ef0ced40 100644
--- a/src/spikeinterface/sortingcomponents/clustering/split.py
+++ b/src/spikeinterface/sortingcomponents/clustering/split.py
@@ -3,7 +3,6 @@
 from tqdm.auto import tqdm
 
 from sklearn.decomposition import TruncatedSVD
-from hdbscan import HDBSCAN
 
 import numpy as np
 
@@ -218,6 +217,8 @@ def split(
         final_features = TruncatedSVD(n_pca_features).fit_transform(flatten_features)
 
         if clusterer == "hdbscan":
+            from hdbscan import HDBSCAN
+
             clust = HDBSCAN(
                 min_cluster_size=min_cluster_size,
                 min_samples=min_samples,