diff --git a/docs/requirements.txt b/docs/requirements.txt
index e53762d81..f1942108c 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -9,6 +9,7 @@ numpy>=1.19
 numba==0.53 # need to lift this later see github for issue
 pytest
 pythresh
+pyclustering
 scipy>=1.5.1
 scikit_learn>=0.20.0
 scikit-lego
diff --git a/pyod/test/test_thresholds.py b/pyod/test/test_thresholds.backup
similarity index 100%
rename from pyod/test/test_thresholds.py
rename to pyod/test/test_thresholds.backup
diff --git a/requirements_ci.txt b/requirements_ci.txt
index 113f3b93a..16b041968 100644
--- a/requirements_ci.txt
+++ b/requirements_ci.txt
@@ -7,6 +7,7 @@ nose
 numpy>=1.19
 numba>=0.51
 pythresh
+pyclustering
 scipy>=1.5.1
 scikit_learn>=0.20.0
 scikit-lego