diff --git a/openml/extensions/sklearn/extension.py b/openml/extensions/sklearn/extension.py
index ce8e4ebf9..9efd8fbb0 100644
--- a/openml/extensions/sklearn/extension.py
+++ b/openml/extensions/sklearn/extension.py
@@ -432,6 +432,7 @@ def _serialize_model(self, model: Any) -> OpenMLFlow:
                                 # annotate a class of sklearn.svm.SVC() with the
                                 # tag svm?
                                 ],
+                          extension=self,
                           language='English',
                           # TODO fill in dependencies!
                           dependencies=dependencies)
@@ -455,9 +456,12 @@ def _get_external_version_string(
             model_package_name, model_package_version_number,
         )
         openml_version = self._format_external_version('openml', openml.__version__)
+        sklearn_version = self._format_external_version('sklearn', sklearn.__version__)
+
         external_versions = set()
         external_versions.add(external_version)
         external_versions.add(openml_version)
+        external_versions.add(sklearn_version)
         for visitee in sub_components.values():
             for external_version in visitee.external_version.split(','):
                 external_versions.add(external_version)
diff --git a/openml/flows/flow.py b/openml/flows/flow.py
index bdd4fe6a6..33102f9d4 100644
--- a/openml/flows/flow.py
+++ b/openml/flows/flow.py
@@ -87,7 +87,7 @@ def __init__(self, name, description, model, components, parameters,
                  dependencies, class_name=None, custom_name=None,
                  binary_url=None, binary_format=None,
                  binary_md5=None, uploader=None, upload_date=None,
-                 flow_id=None, version=None):
+                 flow_id=None, extension=None, version=None):
         self.name = name
         self.description = description
         self.model = model
@@ -131,8 +131,10 @@ def __init__(self, name, description, model, components, parameters,
         self.language = language
         self.dependencies = dependencies
         self.flow_id = flow_id
-
-        self._extension = get_extension_by_flow(self)
+        if extension is None:
+            self._extension = get_extension_by_flow(self)
+        else:
+            self._extension = extension
 
     @property
     def extension(self):
diff --git a/tests/test_extensions/test_sklearn_extension/test_sklearn_extension.py b/tests/test_extensions/test_sklearn_extension/test_sklearn_extension.py
index 2217b332b..bcebe417f 100644
--- a/tests/test_extensions/test_sklearn_extension/test_sklearn_extension.py
+++ b/tests/test_extensions/test_sklearn_extension/test_sklearn_extension.py
@@ -1219,6 +1219,14 @@ def setUp(self):
     ################################################################################################
     # Test methods for performing runs with this extension module
 
+    def test_run_model_on_task(self):
+        class MyPipe(sklearn.pipeline.Pipeline):
+            pass
+        task = openml.tasks.get_task(1)
+        pipe = MyPipe([('imp', Imputer()),
+                       ('dummy', sklearn.dummy.DummyClassifier())])
+        openml.runs.run_model_on_task(pipe, task)
+
     def test_seed_model(self):
         # randomized models that are initialized without seeds, can be seeded
         randomized_clfs = [