diff --git a/ixmp/tests/test_tutorials.py b/ixmp/tests/test_tutorials.py
index 6d82dc395..a2bef07fc 100644
--- a/ixmp/tests/test_tutorials.py
+++ b/ixmp/tests/test_tutorials.py
@@ -1,6 +1,5 @@
 import os
 import platform
-import sys
 
 import numpy as np
 import pytest
@@ -51,8 +50,6 @@ def test_py_transport_scenario(tutorial_path, tmp_path, tmp_env, default_args):
 @FLAKY
 @pytest.mark.xdist_group(name=f"{group_base_name}-1")
 @pytest.mark.rixmp
-# TODO investigate and resolve the cause of the time outs; remove this mark
-@pytest.mark.skipif(GHA and sys.platform == "linux", reason="Times out")
 def test_R_transport(tutorial_path, tmp_path, tmp_env, default_args):
     fname = tutorial_path / "transport" / "R_transport.ipynb"
     nb, errors = run_notebook(
@@ -63,8 +60,6 @@ def test_R_transport(tutorial_path, tmp_path, tmp_env, default_args):
 
 @pytest.mark.xdist_group(name=f"{group_base_name}-1")
 @pytest.mark.rixmp
-# TODO investigate and resolve the cause of the time outs; remove this mark
-@pytest.mark.skipif(GHA and sys.platform == "linux", reason="Times out")
 def test_R_transport_scenario(tutorial_path, tmp_path, tmp_env, default_args):
     fname = tutorial_path / "transport" / "R_transport_scenario.ipynb"
     nb, errors = run_notebook(