diff --git a/eland/ml/_model_serializer.py b/eland/ml/_model_serializer.py
index e9dc26f..976a85c 100644
--- a/eland/ml/_model_serializer.py
+++ b/eland/ml/_model_serializer.py
@@ -94,7 +94,12 @@ class TreeNode:
             add_if_exists(d, "split_feature", self._split_feature)
             add_if_exists(d, "threshold", self._threshold)
         else:
-            add_if_exists(d, "leaf_value", self._leaf_value)
+            if len(self._leaf_value) == 1:
+                # Support Elasticsearch 7.6 which only
+                # singular leaf_values not in arrays
+                add_if_exists(d, "leaf_value", self._leaf_value[0])
+            else:
+                add_if_exists(d, "leaf_value", self._leaf_value)
         return d
 
 
diff --git a/eland/ml/imported_ml_model.py b/eland/ml/imported_ml_model.py
index deed962..23418fe 100644
--- a/eland/ml/imported_ml_model.py
+++ b/eland/ml/imported_ml_model.py
@@ -39,7 +39,7 @@ if TYPE_CHECKING:
     except ImportError:
         pass
     try:
-        from lightgbm import LGBMRegressor, LGBMClassifier  # type: ignore # noqa: f401
+        from lightgbm import LGBMRegressor, LGBMClassifier  # type: ignore # noqa: F401
     except ImportError:
         pass
 
diff --git a/eland/tests/__init__.py b/eland/tests/__init__.py
index f416bf2..44c94c8 100644
--- a/eland/tests/__init__.py
+++ b/eland/tests/__init__.py
@@ -19,6 +19,7 @@ import os
 
 import pandas as pd
 from elasticsearch import Elasticsearch
+from eland.common import es_version
 
 ROOT_DIR = os.path.dirname(os.path.abspath(__file__))
 
@@ -34,6 +35,8 @@ if TEST_SUITE == "xpack":
 else:
     ES_TEST_CLIENT = Elasticsearch(ELASTICSEARCH_HOST)
 
+ES_VERSION = es_version(ES_TEST_CLIENT)
+
 FLIGHTS_INDEX_NAME = "flights"
 FLIGHTS_MAPPING = {
     "mappings": {
diff --git a/eland/tests/ml/test_imported_ml_model_pytest.py b/eland/tests/ml/test_imported_ml_model_pytest.py
index 01018d2..c3a9543 100644
--- a/eland/tests/ml/test_imported_ml_model_pytest.py
+++ b/eland/tests/ml/test_imported_ml_model_pytest.py
@@ -19,7 +19,7 @@ import pytest
 import numpy as np
 
 from eland.ml import ImportedMLModel
-from eland.tests import ES_TEST_CLIENT
+from eland.tests import ES_TEST_CLIENT, ES_VERSION
 
 
 try:
@@ -62,6 +62,14 @@ requires_lightgbm = pytest.mark.skipif(
 )
 
 
+def skip_if_multiclass_classifition():
+    if ES_VERSION < (7, 7):
+        raise pytest.skip(
+            "Skipped because multiclass classification "
+            "isn't supported on Elasticsearch 7.6"
+        )
+
+
 def random_rows(data, size):
     return data[np.random.randint(data.shape[0], size=size), :].tolist()
 
@@ -241,6 +249,7 @@ class TestImportedMLModel:
     def test_xgb_classifier(self, compress_model_definition, multi_class):
         # test both multiple and binary classification
         if multi_class:
+            skip_if_multiclass_classifition()
             training_data = datasets.make_classification(
                 n_features=5, n_classes=3, n_informative=3
             )
@@ -280,6 +289,7 @@ class TestImportedMLModel:
     def test_xgb_classifier_objectives_and_booster(self, objective, booster):
         # test both multiple and binary classification
         if objective.startswith("multi"):
+            skip_if_multiclass_classifition()
             training_data = datasets.make_classification(
                 n_features=5, n_classes=3, n_informative=3
             )
@@ -420,6 +430,7 @@ class TestImportedMLModel:
     ):
         # test both multiple and binary classification
         if objective.startswith("multi"):
+            skip_if_multiclass_classifition()
             training_data = datasets.make_classification(
                 n_features=5, n_classes=3, n_informative=3
             )
diff --git a/noxfile.py b/noxfile.py
index cf00731..194a5a1 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -98,25 +98,19 @@ def test(session):
     session.run("python", "-m", "eland.tests.setup_tests")
     session.run("pytest", "--doctest-modules", *(session.posargs or ("eland/",)))
 
-    session.run("python", "-m", "pip", "uninstall", "--yes", "scikit-learn", "xgboost")
+    session.run(
+        "python",
+        "-m",
+        "pip",
+        "uninstall",
+        "--yes",
+        "scikit-learn",
+        "xgboost",
+        "lightgbm",
+    )
     session.run("pytest", "eland/tests/ml/")
 
 
-@nox.session(python=["3.6", "3.7", "3.8"], name="test-ml-deps")
-def test_ml_deps(session):
-    def session_uninstall(*deps):
-        session.run("python", "-m", "pip", "uninstall", "--yes", *deps)
-
-    session.install("-r", "requirements-dev.txt")
-    session.run("python", "-m", "eland.tests.setup_tests")
-
-    session_uninstall("xgboost", "scikit-learn", "lightgbm")
-    session.run("pytest", *(session.posargs or ("eland/tests/ml/",)))
-
-    session.install(".[scikit-learn]")
-    session.run("pytest", *(session.posargs or ("eland/tests/ml/",)))
-
-
 @nox.session(reuse_venv=True)
 def docs(session):
     # Run this so users get an error if they don't have Pandoc installed.