diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 8cec97b5..e4c2d358 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -98,7 +98,6 @@ $ pip-compile --allow-unsafe --generate-hashes --resolver=backtracking setup.py
 #### Backend
 Update dependencies in requirements-controller.in and/or requirements-jobs.in then:
 ```sh
-$ cd backend/
 $ pip-compile --allow-unsafe --generate-hashes --resolver=backtracking backend/requirements-controller.in
 $ pip-compile --allow-unsafe --generate-hashes --resolver=backtracking backend/requirements-jobs.in
 ```
diff --git a/backend/migrations/versions/420401efbf38_update_variables_pk.py b/backend/migrations/versions/420401efbf38_update_variables_pk.py
index 7b7c4fb8..6cd7f6dd 100644
--- a/backend/migrations/versions/420401efbf38_update_variables_pk.py
+++ b/backend/migrations/versions/420401efbf38_update_variables_pk.py
@@ -33,10 +33,7 @@
 def upgrade():
     op.drop_constraint('ml_model_variables_ibfk_1', 'ml_model_variables', type_='foreignkey')
     op.drop_constraint('PRIMARY', 'ml_model_variables', type_='primary')
-    with op.batch_alter_table('ml_model_variables', schema=None) as batch_op:
-        batch_op.add_column(sa.Column('id', sa.Integer()))
-    op.create_primary_key('PRIMARY', 'ml_model_variables', ['id'])
-    op.execute('ALTER TABLE ml_model_variables MODIFY id INTEGER NOT NULL AUTO_INCREMENT;')
+    op.execute('ALTER TABLE ml_model_variables ADD id INTEGER PRIMARY KEY AUTO_INCREMENT;')
     op.create_foreign_key(
         'ml_model_variables_ibfk_1', 'ml_model_variables', 'ml_models',
         ['ml_model_id'], ['id'])
@@ -44,9 +41,7 @@ def upgrade():
 
 def downgrade():
     op.drop_constraint('ml_model_variables_ibfk_1', 'ml_model_variables', type_='foreignkey')
-    op.drop_constraint('PRIMARY', 'ml_model_variables', type_='primary')
-    with op.batch_alter_table('ml_model_variables', schema=None) as batch_op:
-        batch_op.drop_column('id')
+    op.execute('ALTER TABLE ml_model_variables DROP COLUMN id;')
     op.create_primary_key(
         'PRIMARY', 'ml_model_variables',
         ['ml_model_id', 'name'])
diff --git a/frontend/src/app/ml-models/ml-model-form/ml-model-form.component.ts b/frontend/src/app/ml-models/ml-model-form/ml-model-form.component.ts
index 96aae8ca..2ea0d562 100644
--- a/frontend/src/app/ml-models/ml-model-form/ml-model-form.component.ts
+++ b/frontend/src/app/ml-models/ml-model-form/ml-model-form.component.ts
@@ -414,7 +414,7 @@ export class MlModelFormComponent implements OnInit {
         controls.push(this._fb.group({
           sources: [variableSources],
           source: [existingVariable.source],
-          names: [variables.filter(v => v.source === existingVariable.source).map(v => v.name)],
+          list: [variables.filter(v => v.source === existingVariable.source).map(v => { return {name: v.name, count: v.count} })],
           name: [null],
         }));
         continue;