diff --git a/pylmnn/lmnn.py b/pylmnn/lmnn.py
index 6c61b92..09d3d0a 100755
--- a/pylmnn/lmnn.py
+++ b/pylmnn/lmnn.py
@@ -24,8 +24,14 @@
 from sklearn.utils.random import check_random_state
 from sklearn.utils.multiclass import check_classification_targets
 from sklearn.utils.validation import check_is_fitted, check_array, check_X_y
-from sklearn.externals.six import integer_types, string_types
 from sklearn.exceptions import ConvergenceWarning
+try:
+    from six import integer_types, string_types
+except ImportError:
+    try:
+        from sklearn.externals.six import integer_types, string_types
+    except ImportError:
+        raise ImportError("The module six must be installed or the version of scikit-learn version must be < 0.23")
 
 from .utils import _euclidean_distances_without_checks
 
diff --git a/tests/test_lmnn.py b/tests/test_lmnn.py
index 831a760..29f5fae 100644
--- a/tests/test_lmnn.py
+++ b/tests/test_lmnn.py
@@ -17,9 +17,17 @@
 from sklearn.metrics.pairwise import euclidean_distances
 from sklearn.model_selection import train_test_split
 from sklearn.utils.extmath import row_norms
-from sklearn.externals.six.moves import cStringIO as StringIO
 from sklearn.exceptions import ConvergenceWarning
 
+try:
+    from six.moves import cStringIO as StringIO
+except ImportError:
+    try:
+        from sklearn.externals.six.moves import cStringIO as StringIO
+    except ImportError:
+        raise ImportError("The module six must be installed or the version of scikit-learn version must be < 0.23")
+
+
 from pylmnn import LargeMarginNearestNeighbor
 from pylmnn import make_lmnn_pipeline
 from pylmnn.lmnn import _paired_distances_blockwise