diff --git a/loki/program_unit.py b/loki/program_unit.py
index b5b312e3a..b4797834d 100644
--- a/loki/program_unit.py
+++ b/loki/program_unit.py
@@ -6,9 +6,8 @@
 # nor does it submit to any jurisdiction.
 
 from abc import abstractmethod
-from collections import defaultdict
 
-from loki.expression import Variable, SubstituteExpressions
+from loki.expression import Variable
 from loki.frontend import (
     Frontend, parse_omni_source, parse_ofp_source, parse_fparser_source,
     RegexParserClass, preprocess_cpp, sanitize_input
diff --git a/loki/transformations/tests/test_block_index_inject.py b/loki/transformations/tests/test_block_index_inject.py
index a7fb5c880..26ded84ad 100644
--- a/loki/transformations/tests/test_block_index_inject.py
+++ b/loki/transformations/tests/test_block_index_inject.py
@@ -25,7 +25,7 @@ def fixture_blocking():
     return Dimension(name='blocking', size='nb', index='ibl', index_aliases='bnds%kbl')
 
 
-@pytest.fixture(scope='module', name='config')
+@pytest.fixture(scope='function', name='config')
 def fixture_config():
     """
     Default configuration dict with basic options.